The Epic of Gilgamesh

The Epic of Gilgamesh contains a story that's very similar to the biblical story of Now and the Flood. In the Babylonian story, the flood is sent by the gods and the character who's analogous to Noah survives because one of the gods basically warns him that the flood is going to happen without telling the other gods. So I think that regardless of the historicity of the story, these theological features of the story become apparent when you read it in comparison with the Babylonian version. That's probably really what the story is trying to convey, rather than anything very detailed about a particular historic event that happened a long time ago.