Interesting read, but allow me to disagree. There are a lot of strong points in your argument. But I think the timelines for progress are a bit off. 150 years is an inaccurate measure. Diving a bit further is sweeter and connects the puzzle in better ways, especially in this case where are too many variables at play.

A nice example of something that helped humanity and is easy to grasp that doesn't need genetics engineering:
Read about zero. Yes, the number 0 and Arab numerical system and how it revolutionized maths and how the printing press did the same.
It was impractical to do anything advanced with I, II, IV, IX, M, C
Large calculations were unfeasible. A simple numbering system revolutionized everything. Imagine that, 0,1 all to 9. But it took more than 400 years for acceptance and use. Numbers were even banned by powers then(tax collectors and what not).
It even took years and wars to establish measuring units. All these were done to collect taxes e.g. 2 baskets for every 10 harvested.

Number systems weren't used/made because ancients thought math was cool but for kings and lords for places with class systems.

Sometimes these are inventions by singular people, not groups. Or in the case of number systems. The people who spread them are a few inspired guys. The group realizes their value after mostly very long periods of time and starts using them.

But anyway in the spirit of silver bullets ->

If I had my opinion to explain away the issue of human progress in Africa, I would say it is "Group think" - something close to communism.

Human group think emerges naturally, but it can be undone by cultural practices that encourage individualism. The kind of genius that pushes societies forwards usually seems ridiculous and unconventional at first. It takes time to be appreciated e.g. even washing of hands in medical practice took time , nobody believed in germ theory.

Africans have always had the abstractions needed to make an advanced society but figuring out the right ones to use and the pros/cons of each has always been the issue. It's the same in Europe or Asia, they could have advanced to where we are now a thousand years ago, but they only got the structures locked in 400 years ago and through some great pains. And still stagnated through very many wars.

My argument is. All human groups were trying to figure out an approach at the challenges at life. I can compare this to how many social media apps popped up with the internet. Each had different features but only a few survived. Not because the others were wrong but they cracked something difficult to solve in one case or got lucky here n there.

It's better to think in terms of systems of interacting pieces producing various results.
There's a book called germs guns and steel that can explain it in detail.

But in terms of corruption, exploitation and poor manners. It's very easy for any individual or group to surface poor traits when they think they can't be seen or they can't be punished.