Well, Genesis is taken as the first book of the Bible, however it wasn't written down until after Kings and Psalms. Most of the early history of Judaism was recited in Oral Tradition by wandering muses who would tell thier tales in trade for meals. It wasn't until after the time of Moses that the Hebrews settled and began cataloging and scribing thier history.
To take the Genesis story as literal or a lot of the Bible for that matter can be likened to taking the collective works of the Brothers Grimm as literal. "Jonah and the Whale" and other stories are also fanciful and meant for the campfire.