Generally, sub-Saharan Africans have low scores on IQ tests, educational assessment tests like PISA, etc.
Does that mean that all Africans are the same? No. Could some population in Africa do considerably better, say more like Europeans or East Asians?
Sure: there’s no law of physics that would make it impossible. If local selection pushed in that direction, it could happen.
Has it happened? Maybe on a sub-national,tribal scale. Not on a national scale: every country in sub-Saharan Africa does poorly.
Occasionally I hear people talk about Africa’s great genetic variety. It exists: the genetic difference between Bushmen and Bantu is bigger than the difference between Bantu and Finns. A couple of thousand years ago, before the Bantu had arrived in South Africa & mixed with the Bushmen, it was even bigger: looking at ancient DNA from those unmixed Bushmen, looks as if they split off from the rest of the human race at least a quarter of a million years ago. Well before anything that looks like behavioral modernity, by any definition. Half as divergent as Neanderthals.
But the most divergent populations are small. There are fewer than 100,000 Bushmen, on the order of a million Pygmies, around 1000 Hadza. Most people in Africa are Bantu or related populations: next after that are Nilotic peoples.