Bayek using Senu as a scout might be the origin for the term Eagle Vision. As there's no evidence (yet) that these assassins are connected to Those Who Came Before, there's no reason for Bayek to have the traditional Aura Vision found in other games.
Connor's daughter in the comics displays pretty much the same ability as Bayek does though so it could be an example of the eagle vision we all know and love.
Check out the cover...notice that the pyramid forms the Triangle A cone of the Assassin Logo.
Bayek's status as a Religious Bruiser is strange to longtime fans of Assassins Creed but makes perfect sense when you note Altair appears to have been the originator of their Outgrown Such Silly Superstitions beliefs. This is notably due to his encounters with the First Civilization, Crusades, and other excesses of causes. Other Assassins have included religious members as well, including Connor and Teodora Contanto despite Juno's betrayal.
Why is there a Unexpected Gameplay Change for Bayek from the other entries in the series? Bayek is a professional soldier who knows how to fight with bows, swords, and shields but is not yet an Assassin. As such, he doesn't know how to properly use the Hidden Blade to attack places like arteries or other spots to kill them with. He just knows how to stab people. It's not until he's "leveled up" he knows how to kill people immediately.
The fact many of the individuals you fight wear armor actually may explain why it's so hard to kill them in one blow as that's what armor is for—to keep you from instantly killing someone with a blade. It thus averts Armor Is Useless like so many other games do when not used by the protagonists.
Look at Bayek's main outfit when compared to the 'Protector' outfit obtained later in the game. Notice how they're very similar, with the Protector set almost looking like a clean, non-hooded version of the base outfit? That's because it is. The leather breastplate and shoulder bracer are tattered and faded, like he'd been through countless battles wearing it. The bottom edges near his calves are frayed and dirty, like no regard was given to how clean it appeared so long as it remained functional. He didn't even cut his hair or beard in the intervening YEAR between Khemu's death and the start of the game proper, which for someone in an official government position at that time would've been very much frowned upon. Bayek set out on his Roaring Rampage of Revenge wearing his traditional Medjay attire, and looks to have repaired it with the long vertical yellow sash (which moves as though it's been stitched to the rest of the outfit) and additional red sashes binding the waist after a tear or cut. What did he do with the torn bit? He covered his head with it, probably to keep the desert heat from baking him alive. Basically, Bayek picked himself up and left to seek vengeance with the clothes on his back and little to nothing else... save his weapons.
Usually the games have included a database which provides easy access to information about people and places, but it is notably absent this time. Of course they don't have one! This has gone back a lot further in time than any prior installment. While archaeology has produced a vast array of insight into the society of ancient Egypt, there is still a lot that we don't know compared to say... the Renaissance or the Victorian Era. There is no database provided because it would be extremely limited at best. By the present day, Bayek and Aya seem to have been more or less forgotten until Layla found their genetic memories. A historian can't provide you with background information if absolutely nothing is known about most of the people in question. The best that can be done is to point out the people who have been recorded (as the game does during the introductions of historical figures).
Not to mention that the player character in previous games had some well-equipped support staff, usually Shaun, Abstergo, or Shaun hacking into Abstergo. Layla and Deanna are on the run without the intelligence network of the Assassins; they simply don't have the capability to put one together, even if they did have the historical records.
The Curse of the Pharaohs' afterlives do make relative sense within the canon of the series, despite being rather out-there. As early as Revelations showed that Clay's mind could survive apart from his body in the animus (which is adapted from First-Civ technology in the first place) and Unity implies the same has happened to Desmond as well. III showed that the Isu used attempts like this to survive the cataclysm that struck Earth. Put two-and-two together, and separate "afterlives" holding many deceased individuals makes sense, as they are probably all remaining servers from such a purpose. The characters inside are fairly heavily slanted towards Pharaohs and Priests, who were exposed to the Aten Apple, with civilians likely exposed as well. Since Bayek is implied to only traverse there while the Apple is activated, it makes more sense how they are available in the first place.
Although it is made clear that Bayek is organizing what will become the Assassin Brotherhood, he chooses to call his group the "Hidden Ones." This makes sense when you realize the word "Assassin" has its roots in the Hashashin, an organization that doesn't come into existence until Altair's time. In fact if you pay attention to the dialogue, the script is very careful to avoid referring to Bayek or Aya as "assassins." (We do hear instances of characters mentioning "Assassinations" but this could just be the result of Translation Convention).
Back in Assassin's Creed: Brotherhood there was the "Followers of Romulus" storyline, during which Ezio discovered a suit of armor that is eventually revealed to have belonged to Marcus Brutus. This takes on a new significance when one considers that at the end of Origins we learn that Brutus was recruited as an early member of the Hidden Ones. Remember that in Brotherhood we eventually learn that the Templars stole Brutus's armor and have been passing it off as belonging to Romulus to manipulate the cult- effectively erasing one of the earliest assassins and turning him into a puppet for their own ends. Given Ezio's devotion to the Brotherhood, his defeating the Followers of Romulus and requiring the armor from the Templars feels almost like his way of paying respect to the Brotherhood's history.
According to Black Flag, the individual who they extracted Aveline's memories in Assassin's Creed III: Liberation was a man who eventually died from a seizure due to relieving memories from someone of the opposite gender. One hopes the same fate doesn't befall Layla due to relieving Bayek's memories.
To possibly counteract this, It's implied that the Abstergo research for Desmond's ancestors takes place over the course of several days, whereas Deanna mentions that Layla has only been working on Bayek's memories for a few hours. In addition, the occasional dips into Aya's memories would presumably help to mitigate the opposite-gender Bleeding Effect.
Other consideration to take: That subject was also under the care of Warren "colossal asshole" Vidic, in an older, far more primitive Animus, neither of which would have been good for his health.
Check Layla's journal on her laptop. She complains of having headaches, white-outs, it becomes progressively difficult to stay awake or see her screen and the last entries have a bunch of typos. Despite the advances in technology and the refreshers of dipping into same-gender memories, she's feeling fatigued. Seizures or other side-effects might not be far behind...
Bayek and Aya end their story, essentially, right before the Foregone Conclusion that not only are their efforts to keep Egypt independent ultimately doomed, but they actually brought about the very thing they wanted to avoid. Killing Julius Caesar skyrockets Augustus to power, who proceeds to conquer Egypt and make it part of Rome. He also establishes a dictatorship which lasts centuries after his death. If the future Assassins were behind Brutus and for Egyptian independence—they're in for a nasty future, and they arguably made everything worse. Caesar was willing to give Egypt some sovereignty in both history and AC and he was the only one standing in the way of a long and brutal Civil War.
The previous games established that Juno could take over networks as a digital ghost, and some characters make note that the amount of stuff connected to internet grows larger every day. This game confirms that Assassin's Creed shares its universe with Watch_Dogs, where practically everything, pacemakers included, is online and can be hacked by normal humans. Bravo Blume, your magnificient invention is just what a human-hating precursor needs to destroy us, either by turning entire cities offline at once, driving us mad by showing us stuff human minds literally cannot comprehend, or something even worse.
Going by what happens during Curse of the Pharaohs, it's hinted that anyone who's held an Apple of Eden is imprinted on the thing, with a copy of their minds uploaded into it. They don't even have to use it, just touch it. ... now, how many people over the franchise have we seen using Apples, again?
As the story progresses Layla's journals get less excitable and more concerning, particularly in regards to her health. As the story goes on she gets more and more irritable. She complains of having headaches, white-outs, trouble seeing the screen and the last entries have various typos in them. She's clearly pushing herself to the point of exhaustion if not struggling with a progressive Bleeding Effect. But without Deeana monitoring her she might not stop, she might not realise how much she's pushing her body, it's possible Layla could have worked herself comatose inside her conveniently sarcophagus-sized Animus. She's in one of the remotest parts of Egypt hooked up to a life-support machine without anyone to check on her condition. What would have happened to her had William Miles not found her?