http://www.huffingtonpost.com/jeffrey-small/mythology-and-the-bible_b_898253.html
Neat piece and worth a read. Happen to be reading a book about Near East mythology right now and from a historical perspective, the accretion and adaptation of these stories makes sense. Add in the salvation story from the time of the Babylonian exile and the Bible is the result.
It's fascinating to see the thread of Sumerian mythology woven into Genesis. The battle with Tiamat - the chaos dragon - and the sequencing of Babylonian ritual define Genesis I. etc
Why was Moses so important to these people? Because the Jewish aristocracy was stuck in exile in Babylon.