Africa lacks the easily navigable major rivers that mark much of the rest of the world, except for the Nile. There's the Congo but it was never an easy river to deal with. It is exposure to trade with alien cultures and even warfare that makes civilizations. Without trade you get static tribalism, without trade routes new ideas don't come along very often. Traders bring ideas, conquerors teach ideas, and victors return home with ideas, but people in isolation, however peaceful their existance may be, tend to stagnate. There's no need for innovation, no influx of new ideas, etc. They develop, but very slowly because there is no pressing need for solutions.
Thomas Sowell has an interesting book called COnquests and Cultures, IIRC, that is worth a read for its discussion of how geography, trade, and warfare influenced various civilizations around the globe.
Okay, Okay
there was one civilization. A very brief one.
Some would say Egypt was another, which is a huge lie....
Lets look at meso America...so in comparison for all Africa....