America is the only country in the world with a genuine race problem insomuch as the white establishment feels they owe something.
Anywhere else in the world, blacks would be castigated for trying to pull some BS like this. I agree that they should be thanking us. Had those landowners not brought over boatloads of slaves from Africa to till their fields, an overwhelming majority of modern day black men and women would not even be alive.
Subsaharan Africa was and still is a brutal area of the world.
Slave importation into the states was banned in 1808 so land owners did not do what you said. But slave importation into the Caribbean did continue with Northern businessmen, shippers, bankers, college founders, and government officials doing the lucrative business of keeping slavery alive.