As a Wild Mass Guessing subpage, all spoilers are unmarked as per policy. You Have Been Warned.
The world is in an eternal cycle.
In this movie we see mankind start out innocent, become corrupt and overpopulate and then be killed off by God. We see that this has happened before and we are given the implication this will happen again.When God kills off most of humanity in Genesis and brings the others into heaven the same cycle will occur with mankind eventualy being corrupted and consuming heaven as they did earth.- That's an interesting possibility, but means the rainbow "I'll never do this again" is a load of bull. (Of course that's never pointed out in this movie, specifically.)
- This is supported by the montage narrated by Noah close to the end of the film when he describes mankind's tendency towards violence, showing various attackers from different cultures and time periods attacking another, among them Roman, Egyptian, and Native American warriors, different types of knights and their Middle Eastern counterparts, samurai, and colonial-era foot soldiers.
- Unless Noah had a vision of the future, which he was trying to prevent by allowing he and his family (the last supposed humans) to die out.
- Or the montage was purely for the viewers' benefit, not something Noah himself ever witnessed or imagined. Noah never saw planet formation or animals evolving from one form to another, either.
God shuffled most of the continents around during the flood
In the Astronomic Zoom the world is shown to have all the continents together. They were moved to their more modern positions during the flood. Ila carries the dormant wizarding gene
Her descendants obviously include Hermione Granger. In Noah's era, pregnancy lasted shorter than nine months.
That's how the descendants of Cain became so very numerous in the 10 generations between Adam and Noah. Also better fits the amount of time the ark was probably afloat (ambiguous in the film, but nine months would be a long time to keep Tubal-Cain secret on the ark.)- In the original scripture, people lived for many centuries back then, so people could have dozens if not hundreds of children. A generation could then be measured in centuries instead of our modern ~25 years interpretation.
Ham is going to find other survivors of the flood, while Walking the Earth.
Ham meets Deucalion (no not that one) and Pyrrha and Utnapishtim and his wife. All the animals Tubal-Cain eaten or killed were extinct animals.
In the graphic novel, there's sabertooth tigers and woolly rhinos.- They probably also include mythical creatures, or animals that are supposed to be taken as mythical, such as the scaled dog-like mammal at the beginning (my first thought was a catoblepas). Furthermore, the slaughtered animal that Noah saw just before Tubal-Cain attacked him on the Ark looked an awful lot like a dinosaur to me. A small one, but a dinosaur nonetheless!
The Cainites are Neanderthals
A formerly populous culture that died out, no confirmed survivors in the world afterwards, primarily carnivorous...all they're missing are the pronounced brows. God wanted the human race to survive.
God wished for Noah to also rescue as many good people as he can. But He predicted that Noah's faith in humanity will dwindle, believing they don't deserve a second chance. To help Noah and ensure the survival of humanity, He made sure Ila would be found by Noah after her parents were killed, so then she and Shem would fall in love, get healed by Methuselah, and give birth to twin daughters. Knowing that seeing his granddaughters would shake him out of his funk. The film is not set in actual biblical but a post-apocalyptic Earth
The setting is set in a Used Future, the society that the Cainites have a highly advanced society by the looks of it. There is also a shot of a suspiciously sci-fi looking piece of architecture. There's also the clothing which looks more fitting for a post-apocalyptic Walking the Earth story. The characters just have names that are reminiscent of the Bible for familiarity's sake. Also the Watchers could easily be some form of extraterrestrial Energy Beings. The story of the film is written by Izzy of The Fountain
As pointed out on the main page, there are a lot of similarities between Noah and The Fountain. Since the supernatural sub plot of The Fountain is a book written by Izzy, those similarities could be an In-Universe case of Author Appeal. Taking that into consideration, Noah could even be set in the same world as the in-universe The Fountain book. This movie depicts Jay and Silent Bob's interpretations of the Biblical story.
The movie was clearly written by stoners who picked up a Bible, and maybe went to Sunday school, as Jay and Silent Bob did between Dogma and Clerks II. Watch this movie and tell me it's not something those two space cadets would cook up after a stoned Sunday school lesson.