I took a Mythology class many a year ago, that focused mostly on Joseph Campbell's Jungian interpretation of myths. In case anyone doesn't know, Jung and Campbell believed myths were personifications of our subconscious, although Campbell believed in a deep spiritual message in myths as well, and was, I believe, a devout Catholic. I'm not sure I buy it all, but Joseph Campbell makes for a very good read.
The Hero With a Thousand Faces and
The Power of Myth were both excellent reads.
Anyway, this is what Campbell had to say about the Flood:
Joseph Campbell:
CAMPBELL: Yes. There are very few cultures that don’t have a Flood motif. That’s a basic idea: the dissolution of the world which takes place every night when we go into the flood of our own unconscious. It’s the analogue of the mythological Flood: at the end of the cycle, there’s a flood. The American Indians have lots of Flood stories.
It was thought when the diggings in the Tigris-Euphrates Valley were proceeding that evidence of the Biblical flood could be located – at least a flood universal to that area. And there were flood levels found in several cities. But they were not the same flood level; they were local floods. There’s no cosmic flood; the Flood motif is a mythological idea. The whole notion that all originates from water, and all is going back to water, gives you a cycle: out of water, back to water, out of water, back to water; and each new cosmic aeon, each new world-age, is, as it were, a creation out of water and a dissolution into water. So it’s a mythological motif. This is exactly the point that Thomas Mann makes very well in the first part of Joseph and His Brothers: the archetypal Flood is a mythological, a psychological flood, and when local floods occur they become identified with it. Do you understand? We have experienced The Flood. The Flood is a mythological principle, and when a flood occurred, we understood the sense of the image.
Jung, on the other hand, believed the flood was symbolic of a womb (if memory serves). That one seems a little more far-fetched to me. Personally, I doubt the veracity of a historical world flood, because I assume there would be some sort of archeological evidence left behind. But given that localized cultures in the pre-global world would have experienced devastating floods across much of their land, I can imagine how it must have seemed like a world flood when it first happened.