Anne Bonny(red head) and Mary Read(black hair) are two Ship Tease for Edward who is married to Caroline first, who is a redhead and his second wife, Tessa, mother of Haytham, must have had dark hair which her son couldn't have got from his blonde father. Edward's fondness for Anne at the end of the game, especially his insistence she come to England with him(since his wife his dead at this point) might stem from a desire for a Replacement Goldfish for Caroline, while his continuing devotion to live to Mary Read's promise might have led his attraction to Haytham's mother, since Mary has some resemblance to Haytham, which makes Tessa his Replacement Goldfish for Mary Read.
The pose on the cover of the game, and on the title page with Edward holding his swords on a sloping downward arc forms the distinctive Assassin A. More importantly, when Edward unsheathes his dual swords he holds it in the same way in the game. Imagine the Templars seeing Edward running and fearing the incoming deadly Assassin sigil itself.
And with that pose being an equilateral triangle instead of an isosceles more indicative of the Assassins there's also reference to any of the three Abstergo logos.
From a simple gameplay perspective it might seem odd to go back to the regenerative healing system that was done away with after the first game. However this simple gameplay choice is actually an inversion of Gameplay and Story Segregation. Alta´r's memories were relived through Abstergo's animus system while those of Ezio and Connor/RatonhnhakÚ:ton were essentially enacted in one reverse engineered by the Assassins. Now that the player character is back within the walls of Abstergo Industries their gameplay within the Animus is dictated by their software standards... including regenerative healing.
Actually, it makes sense: the Templar interface has always had the regenerative interface, so we're simply going back to normal. The Assassin interface has only recently started using it, aka ACIII, where the go-back oddity started.
Some of the lyrics of tavern songs tend to have connections to Edward's own life and moods, which explains why he seems to have frequented them aside from being The Alcoholic. The song, Burn the Candles Out, a bawdy but sweet love song about a woman and man making the best of their privacy has some similarities to Edward and Caroline's relationship. Especially this refrain, where the wife promises to give birth to a baby to greet him when they meet again next time. Which almost Foreshadows the end of the game.
"I like well your behaviour*
And this I often say
I cannot rest contented
When you are far away"
The song The Trooper and the Maid even foreshadows the end:
"It's when will you come back again
My own dear soldier laddie
When will you come back again
And be your bairnie's[baby's] daddy''
Really Black Flag is perhaps the first Video Game musical.
Aesop's Fable of The Eagle and the Jackdaw is a running motif in the game with obvious parallels and symbolism of Edward and the Jackdaw. But here's Fridge Brilliance, what are the names of the two ships you pilot in the series. The first ship you pilot is called L'Aquila, captained by Edward's grandson. L'Aquila means you guessed it, The Eagle. In other words players, in Anachronic Order, first captain The Eagle and then the Jackdaw in the course of one century.
And of course Edward's son Haytham has a name which means "young eagle", and he wanted him to be an Assassin. So the Jackdaw wants his son to be the Eagle he never entirely could be, only, well that doesn't quite work out. But Connor ends up becoming a true Assassin and the Eagle that Edward hoped that Haytham would be. Maybe, Kenways are to be judged not by their names but the names of their ships?
A bit of Gameplay and Story Integration tying into Assassin's Creed: Forsaken. Why was Edward so easily killed by a bunch of mercenaries?. Well, not only was he not wearing any of his special armors from the game — neither the Templar Armor, the Mayan Armor, OR his many Health bonus providing animal-skins — but he's also protecting his wife and son. In other words, it's an Escort Mission. Given how vulnerable Edward is during diving missions without his armor, it's easy to understand why one of his opponents got lucky.
The name of Adewale's brig in the Freedom Cry DLC is Experto Crede, Latin for "Believe the Expert"... amazingly fitting considering his role relative to Edward in the Jackdaw as not only Sergeant Rock to the crew but also the Only Sane Man compared to Edward's excesses.
I'm really sick of doing mindset work for Fridge Brilliance so long story short: Is there a Corvid Trope that doesn't fit Edward Kenway?* Rhetorical question.
A rather nasty real-life one is the talk about the kind of burns and horrific conditions that sugar making slaves had to endure when you move to rob the plantation. It's bad enough Adewale had to endure that sort of suffering himself. The Fridge Horror kicks in when you realize not only was it a real life horror but it happened to thousands, if not millions, of people who weren't nearly as lucky to escape the life and become freebooters.
This becomes Ascended Fridge Horror in the DLC Freedom Cry where the Plantation missions revolve on freeing the slaves rather than robbing the owners dry. They also give an in-Universe justification, Adewale says that after running away as a slave and joining pirates, he wanted to get away from anything that reminded him of slavery and its only years later, as an active Assassin that he's able to deal with his Dark and Troubled Past and deal with it head-on.
Further horror, when Kenway and Vane are tailing a slave galley for the Royal African Company, and undergo the Mutiny. That ship is a slave galley with slaves below deck, Adewale specifically warns Edward not to fire broadsides for fear of hurting lives beneath. Well, after the Mutiny, they take over that ship, with Rackham promising to sell Adewale for "a tenner". What happened to the rest of the people underneath, who we don't see? The obvious answer is that Rackham and Co. sold them too and then pissed away all that money on alcohol.
Another slavery related one. You can raid plantations and kill absolutely every guard there. However, the slaves just carry on with their work with the implication being that they've been so badly broken as human beings that they won't try to take freedom even when they have the chance.
The gameplay insists you shoot down several ships, murder surrendering captains of forts with you only impressing a few of the captive sailors into service aboard the Jackdaw. Which means you pepper the Caribbean Sea and make shark food out of several poor sailors not any different from Edward essentially, yet Edward is the one who retires in England with a mansion, wealthy wife and beautiful children. It's weird to actually play a Karma Houdini(Assassin's Creed: Forsaken nowithstanding)
The Foregone Conclusion element of Edward Kenway's children, made doubly worse by Assassin's Creed: Forsaken. Even if you don't consider the novels to be canonnote writer Darby McDevitt and director Ashraf Ismail confirm it is, eventually Edward's Assassin grandson will murder his Templar son. Worse still, Edward's distant descendant Desmond will die at the hands of Juno. Which wouldn't be so bad if not for the fact they mine his brain to undo Edward's life work.
More Fridge Horror, its implied in Assassin's Creed III that Haytham initiated The Purge on the Colonial Assassins. We don't know how far that reached. The Remnant exists in Assassin's Creed III: Liberation in Spanish Louisiana but considering that the Naval missions in III has Connor visiting Belize and the Caribbean, and Achilles Davenport has Caribbean descent, and those waters are filled with Templar privateers its possible that Haytham purged his father's old associates there. Can you imagine the horror of Edward's own son purging his former associates? Related to this, how come none of them tried to remind Haytham of his roots?
Achilles (and others like him) may be at partially fault there since his general attitude to the Templars was Kill 'em All. Haytham implies is all the Assassins do in the 17th century, which carries over to the Modern Era. This is backed up by the fact anti-slaving Assassins like Aveline and Adewale have to do their activities as a side-job despite it being tailor made as an activity for followers of the Creed. Edward's closest friend in the Assassins, Mary Read was also dead so it's possible they didn't really feel much loyalty to the man. Haytham's messianic delusions of uniting the Assassins and Templars probably didn't win him any friends either.