>>516094603 (OP)
I'm not even racist, personally, but I think it has a lot to do with the cultural context in which a nation finds itself.
Some nations live in highly dense and turbulent regions that facilitate a lot of trade between different people and cultural diffusion. The Indians lived on the ganges and had to deal with the interplay between Indo-Aryan migrations and the Dravidian natives. Egyptians lived on the nile and dealt with trade with the entire mediterranean, Assyria, Greece, ect.
In all of these cases a civilization rose in a multiethnic region with large waterways and an imperative to expand and establish trade relations to survive. In the very long term, this congregates the discoveries and technologies of different people as ideas and good spread and are copied. It isn't any wonder that Europe became one of the most developed places in the world considering it connected so many coasts and river civilizations in the relatively enclosed med sea. Africa is largely a garden of Eden with a lot of food sources and a limited amount of natural coasts which would've facilitated trade relations with other peoples(outside of east africa, which notably became one of the most developed subsaharan regions historically). The sahara desert to the north prevented extensive travel, so Africa was functionally stuck in the stone age far longer than other people due to a lack of a need to socially progress like other civilizations had.
Unlike say, Japan, which had a very complex medieval culture when they were exposed to the western world, Africa was functionally still at stage one. I recall a story about marines in Afghanistan discussing how Afghans had no concept of standing in line, and they referred to standing in line as a "social technology". The capital and intellectual investment required to elevate a population to a genuinely first world standard in cultural norms could take several generations .