I think that the Old Testament is basically 'true' in that everything in it happened. They're stories belonging to a particular agriculturalist people refracted, beautifully and metaphorically, through generations of retelling. It's very common for stone age and iron age peoples to remember even recent history in a sort of mythical way, partly because they quite literally understand time differently.
I don't actually know a whole heap about Middle Eastern culture of the late stone age and the early iron age but I do know that there were pastoralists (herders), farmers, expansions and displacement of people, and we remember them thanks to experts in oral history and the people who finally wrote down what they passed on.
For various reasons, agriculturalist societies tend to be more robust, and far more in need of land, than herding people. Agriculturalist people go looking for land to seed and they don't share it with herders. This happed recently in South Africa - less than 2,000 years ago - and when you look at myths of origins there you can often map it to places (rivers and mountains) that really exist. The stories seem to correspond nicely to the archeology. The mythical tone reminds you very much of the stuff in Genesis.
In Southern Africa there were a herding people called the Khoekhoen who lost their land to Bantu-speaking peoples like the Tswana, the Zulu and Xhosa. 'Xhosa', in eastern Khoe dialects, is phonetically identical to a word meaning 'angry men'.