Which was a direct result of European slave trade in Africa

A very direct result was the fact that a lot of slaves were being transferred to the US where they were sold in slavery. For that reason, it was very prosperous in the US for certain people as they were able to afford slaves. The opposite happened in Africa, where the slave trade brought upon a lot of issues and problems.

One of the direct result of European Slave trade in Africa is that it Promoted a feeling of racial superiority among Europeans.

That's probably what's causing the European countries became the first one who sell black skinned people as slaves.