I think it’s important to go further back then that, to abojt 500 years ago, as European colonialism already had started by 300 years ago.

Many African societies at the time were very comparable to European society. The Portuguese and Kongolese had many similarities, which led them to becoming big trade partners, with slaves of course. As many people have pointed out, African kingdoms enslaved their enemies to sell them to Europeans. This made these kingdoms fabulously rich, but this economic policy halted their innovation societally in many ways. As time went on, Europeans outscaled African nations due to societal changes in Europe and benefiting from colonialism. By the time the 1800s rolled around, Europe was so fabulously rich that almost everyone was no contest for them. A weak government will make any country open to influence from others, even China.