What is more likely is that there is truth to the garden of eden story, we came up in a forrest or jungle straddled by two rivers likely in what became ancient mesopotamia and after thousands of years we had chopped and burnt all the trees down and violently driven other tribes out and out further, prey animals get hunted to extinction causing more exoduses. After eons the ethno groups that moved north and east are just different species and the ones that went south get locked behind the sahara as it becomes a larger impassable desert and breed with our ancient cousins. By the time they want north again a pre-Egyptian civilization owns the nile and blocks passage up from the south Our pre hominid ancestors likely did come out of africa but our humanoid ancestors likely developed outside of africa and quickly spread out from the garden and those rhat were left there destroyed the causing a second major exodus period. These two exoduses are what created the europeans, caucasians and east asians, Denisovans and Neanderthals settled far away from the garden were encountered by the people fleeing its fall. To be clear the garden was likely spewing people forth across the world following rivers snd coasts the whole time but major exoduses probably did happen as I have suggested.