In the alternate Noah's Ark story as told by the Man, when the dove did not return everyone on the boat just....waited. Waited until they'd forgotten a bird was sent out, that there was a world before/beyond the Ark, that the animals originally brought aboard turned to stone...until they forgot themselves and turned to stone as well.
Now look at the girl, she needs to eat and sleep like a regular person does but her skin and hair are paper white. If she stood still she could be confused with some marble statue from afar. Side effect from living in a world that is perpetually dark and cloudy? Also she's been wandering about on her own for so long that she's collected water into glass bottles by the hundreds, that she's forgotten her own name and the reasons for why she's there or doing what she does.
Not to mention her clothing, a long and heavy dress with slip that looks like it was meant for someone much larger. It could even be a tunic ensemble she's just wearing as a dress. Alongside a simple shawl and a messenger bag, pretty old school wear despite the town she's in looking like it's from a much more modern era.
So. What if she's the last of the original passengers from this version of Noah's Ark? In the bible there are multiple instances of humans/god's chosen peoples/"protagonists" living for hundreds of years and such. This could easily apply to her, as well as make the tale a bit more literal than one might think.
She wanders all over the town and the inside compartments of the ark, that aren't flooded anyway, as she knows them intimately. Inhabiting a world that has turned to stone and shadow around her, with the girl being the last hold out due to her own personal nature. The hope she has of hatching that egg could even be a contributing factor to this- since we have no idea how long she's had the damn thing.
How if the idea ia true, that means she's the last "good soul", the last of those chosen to survive the damn flood, than that means she needs to be saved. Or should be, because she continues to believe in the world. In the bird/angel being.
And then, along comes the man. Summoned/placed by an ominous and god like eye/space ship thing and having a lot of Jesus-like attributes to his demeanor/design and seemingly on a mission....that he no longer remembers. Perhaps this was intentional, his amnesia would allow the girl to relate and trust him more easily...or something.
Anyway, after everything he breaks her egg. Her last tether of hope/purpose in this empty world is cut. And thus she is cast from the world, freed from the child's form she'd had up to this point and her soul/being can be free to grow and move beyond. As represented by her turning into a young woman of possibly similar age to the man.
But that is not the end, with her last breath come a multitude of eggs. Which root into the ground and begin to grow, as a possible sign of a second age coming to this world.
This whole thing takes place in the distant past, telling the "real" story of Noah's Ark. (For the purposes of this story, the Bible is considered inaccurate.)
The story begins like the tale of Noah's Ark. God felt that humans had grown wicked, and he regretted creating them, so he destroyed the world with a flood. Only the most pious people were allowed live on an "ark" so they could survive the flood. It turns out, however, that the ark is actually a gigantic boat-shaped island instead of an actual boat, and presumably it was crafted by God himself instead of being hand-crafted by Noah and his family. (In fact, it's not clear that there was ever an individual "Noah" in the first place; apparently God just left the island to thousands of people he deemed worthy of surviving the flood.)
The catch here is that God didn't plan on giving earth back to humanity automatically. First he wanted to see if his chosen people actually loved him. But it turned out that even the chosen people were defiant. They were angry at God, perhaps because they didn't approve of him destroying most of humanity.
Fish are a symbol of God in this story. They became a symbol of God because God destroyed the world with a flood, thus killing pretty much everything except fish. The shadow-fish we see are signs of God's presence. It's God's way of testing the people to see if they will worship him. (Let's just assume he explained the symbolism to the people at some point.) But the people hate God, and thus they hate the fish. They throw their harpoons at the shadow-fish with all their strength, but they don't do any damage. This symbolizes how mankind cannot resist God, being that he's omnipotent.
This state of affairs goes on for generations. God keeps waiting for the people to worship him, and the people keep refusing to do so, and everything gradually falls into decay and despair. The girl also states that "the fish are gone, but the people still attack them". God used to send actual giant fish, back when the flood had happened just recently. In the centuries since, God has become less and less willing to reach out to humanity, because they've defied him for so long. He can't be bothered to send actual giant fish anymore, so instead he just sends shadow-fish. But humanity still hates him.
God originally created large birds whose purpose was to inform humanity that they had passed the test and thus God would remove the flood and allow humanity to retake the earth, but humanity has persistently failed the test, and eventually all the birds died or turned to stone.
The girl and the man are both angels. They've lived on the ark so long that they've both developed amnesia and lost most of their angelic powers, but one power they've kept is that they don't grow older. The girl has hope for humanity, and guards an egg in hopes that it will hatch and have a purpose as God's messenger, finally delivering the good news that the flood is over. (This might happen if humanity decides to accept God or if God decides not to demand their worship anymore.) The girl has forgotten the details of all this but she knows that the egg is important. The man, meanwhile, has no hope for humanity. He believes that God should destroy the remaining humans and move on entirely, because humanity will never truly deserve to live. He too has forgotten most of the details, but he can sense there's something important about the girl and her egg, so he follows her around.
The movie is called "Angel's Egg" because the girl is an angel. The egg is an "angel's egg" in the sense than an angel is guarding it.
The girl drinks water, but the man refuses. The girl sleeps, but the man does not. Angels don't really need to drink or sleep (at least not when they have their full set of powers), but the girl took up the habit of imitating human frailties a long time ago, as a sign of how much she identifies with the human race. The man, meanwhile, thinks humanity is worthless, and thus never took up these habits. (Neither one of them fully remembers all this.)
The man eventually recovers some of his memory and smashes the egg, expressing his belief that there is no hope for humanity. In response, the girl decides to sacrifice her own life for humanity's sake. She destroys her own angelic body in such a way as to create many more eggs, so there will always be a way for God to reconcile with humanity and fulfill his original plan of letting them walk the earth once more.
God is moved by this act of self-sacrifice, and memorializes the girl as a statue. The other statues may likewise represent angels who previously did good deeds; perhaps the rest of them gave their lives to defeat Satan or something. The girl is the only angel depicted with an egg, for she is the one angel who specifically died for the sake of humanity.
Some time later, we may assume, things work out between God and mankind. One of the eggs hatches a bird which is eventually ordered to bring humanity the good news: God has accepted you, the flood is ending, and you may walk the earth once more.
The girl had distinctive white hair, and the color white is actually a combination of all colors. If you shine white light through a prism, it becomes a rainbow. Once humanity is freed from the flood, God places a rainbow in the sky (Genesis 9:13-15). This serves as a sign to the people that he will never again flood the earth, and it's also a reminder to himself of the noble angel who always kept her faith in humanity, and who inspired God himself to give mankind another chance.
Several centuries later, God incarnates as Jesus Christ. In the form of Jesus, he adopts human frailties like the girl once did. As the Holy Spirit, he briefly incarnates as a bird (Matthew 3:16), again in tribute to the girl. Finally, Jesus sacrifices his own life for the sake of humanity, just as the girl sacrificed herself all those years ago.
This is the story of an angel who inspired God.
