So you think that Black people are inherently inferior, just not inferior enough to be bought and sold as slaves.
There were many benefits of slavery, though certainly not for most Black people. The entire South was built by slave labor on cotton and tobacco plantations in a relatively few years. Observe how long it took Canada to be cleared and settled, with only White folks. The plantation owners were a very small percentage of the Southern population, but they prospered immensely, and then lost most of it when they decided to secede.
The major differences between the various "races" are cultural. Black people were divided into many more linguistic groups than were White people in Africa as well as when they arrived here as slaves. That explains the differences in development in Africa. In the US, the legacy of slavery and racism were and continue to be what is holding back Black people.
The most prosperous countries with a majority Black population are Trinidad & Tobago, The Bahamas, Bermuda and Botswana. In each of them there is a common language and a great respect for education. South Africa has a variety of languages and traditions that are in conflict with one another, but a great potential. And of course, Brazil has more Black people ( or at least people that would be considered Black in the US) than any other single country in the planet, and seems to be doing much better now that it is trying to distribute resources more equitably.
Columbus never sailed around the world. That would be Magellan and Elcano. Columbus only sailed from Europe to the Americas four times: he never dipped even one toe in the Pacific.