I think I agree with parts of what you said, but I'm not really sure I completely understand what you're saying. No offense intended.
I prefer to see the formation of Israel in this way: it's like preparing a field for the harvest. You till the ground, remove rocks, weeds and other obstacles, fertilize it, and one day it's prepared for planting. In this case, the perfect seed was Christ and His church.
To facilitate this, and to keep it as pure as possible, the nation needed to somehow set itself apart. God did this through the Law, and through the stories of shared history that illustrated God's place in the world and theirs as well. You see stories, like the creation story, that set them apart from Mesopotamians. You see stories like Lot with his daughters that set them apart from the Canaanites. You see stories like Joseph's that set them apart from the Egyptians. Do these stories need to be 100% true? I have no doubt that most came from actual events and people, but I also have no doubt that those stories were shaped to make the point God wanted in ways that weren't 100% accurate.
I'd hope we all agree on this: whether or not the stories are true, the messages that God wants us to take from them are identical for everybody. I seriously doubt that God inspired the creation story to tell us exactly how creation occurred; he wanted to specify both His and our place in it.