It's more complex than that.

Africa is a very diverse continent, and slave traders mixed a bunch of tribes and degraded them over centuries to what they've become today. They gave them a shared "culture" that was not theirs before.

Doesn't have to do with their skin, although it does have to do with their race but not to the extent that you attribute to it.

It's a complex problem, and you need to think about it more deeply if you don't want to sound like a flatearther when discussing it.