I figured it was sort of an Adam&Eve type thing.

Also in Norse Mythology, when the Ragnarok apocalypse finally occurs and the world sinks into the sea, a single human couple is supposed to hide away in Yggdrasil, the ultimate, world tree, and come out at a later time, to reseed the world, supposedly, like a cyclical Adam&Eve.

You can't have an apocalypse film without an element of rebirth/feedback loop. Like in Akira, when the movie ends with the big bang.