They didn't steal from the Africans, for the simple fact that there was nothing worth to steal.
Europeans didn't exist. There were several, but not all, European nations involved in long distance exploitation. They didn't set out with the goal to rob the natives blind. The intentiona was to trade. Something valuable from then for something valuable from us.
If they accept beats and mirrors as valuable, who are the we to correct them? Are you going to argue in a shop that the price is ridiculously low? Are you going to insist they must accept 5x the asking price? If you do not, why do you insists others do?
The goals were to discover and explore possible trading routes to China. Do business along the way. The cultural differences between those tribes and the sailors was enormous. Stealing was not in the program. Thieves on board were severely punished.
European nations became the most advanced nations simply because they invested in research and development. Even if they wanted to steal technology, they had to sail to India and China to get something worthwhile. In Africa there was nothing worth the trouble. That is why Africa was the last continent on the planet to be discovered (by Europeans).
Please get your facts right. You are looking with the fashionable politically correct ideology to events that happend half a millenium ago.