The people , as many as there are on that vast continent could never get organized long enough to demonstrate organized farming and a structured existence known as civilization.
Tribalism and warring has always had greater importance, let alone their total African philosophy that no one can get ahead of the chief... sorry chiefs... as many communities have a chief by day and another for the night.
Their failure is in their black persona and has been going on since the beginning of time. Anyone who points at the whiteman for the blacks failure is only a race baiter. They dont need a whiteman to fail! For them oppression starts at home in Africa!
Africa only has a handful of navigable rivers, and the livestock diseases make use of draft animals impossible for much of sub-saharan Africa. It was not until Europeans introduced the Railroad in the 1870s that Africans could carry trade goods by any means other than on their backs.