Some interesting points about Genesis 1-11: (a) There's no devil, just a talking snake. (b) The evil in the world comes from God or from mankind because that's how it turns out humans had been made. That's why got regrets making mankind and decides to kill everyone but eight people. (c) Aside from a prohibition on eating blood and killing other people, there's no rules. Oh, and whatever you do, don't look upon your old man's nakedness.
It seems to me that these stories are a thin reed on which to predicate the narrative of the Fall of Man. Man didn't get thrown out of the garden because he was evil; he was thrown out because he became aware of good and evil. If mankind had continued to live in blissful ignorance, presumably we'd still be in the garden.
Chapter 12 of Genesis is where the OT really should start in my opinion. This is where a continuos narrative can be found to begin. Here's the meat:
Go forth from your country, and from your relatives and from your father's house, to the land which I will show you; and I will make you a great nation, and I will bless you, and make your name great; and so you shall be a blessing; and I will bless those who bless you, and the one who curses you I will curse. And in you all the families of the earth shall be blessed.
This is God's promise to Abram. He's talking about Canaan and the whole land from the river of Egypt to the Euphrates. Abram's descendants will be as numerous as the dust of the earth and occupy the promised land forever.
As an aside, Abram goes to Egypt because there's a famine and Egypt is the go to place in lean times. There he passes his wife off as his sister and she ends up with Pharoah until the truth comes out. Abram gets kicked out of Egypt.
How did the author of Genesis 12 know that God said these things to Abram? Someone told him so. This was doubtless part of an oral tradition for many years before it was written down. The author was not an eye witness to the event. Certainly, the descendants of Abram ultimately took possession of the promised land and, assuming that Arabs and Jews are descended from Abram, occupy the promised land and more to this very day. And there are lots of them, not yet as numerous as the dust of the earth but potentially as numerous with time. Since, as I believe, all that occurs is God's will, one might easily imagine God's announcement to Abram of what would come to pass. Was such an announcement made? God alone knows. Does it matter?
For all we know, God went around announcing His intentions in those days all over the place. Other progenitors may have been promised tracts of land and reproductive success but it didn't get written up. Anyone who didn't have reproductive success would not have left descendants to speculate on whether God had announced anything to their ancestors.
The key point for me is that the storytellers began to see the blessing of Abram as part of a greater narrative in which the children of Abram are to be a blessing to all the families of the earth. There's a plan unfolding. Now the OT is about to get interesting.