I agree that slavery was a repulsive institution. Jefferson, a slaveholder himself, agreed as well, and denounced it eloquently. He foresaw the problems that trying to integrate two diverse populations into one free country would bring, though, and favored repatriation to Africa.
Lincoln too favored repatriation for much of his life, and even after emancipation reassured Northerners that if the freed blacks started swarming north, they could simply be refused entry (though there’s nothing in the Constitution about that, and it didn’t turn out that way).
A little diversity usually helps a country, but having large subgroups tends to cause problems. After centuries of living together, though, American whites and blacks should be able to get along within the borders of the same country, and even within the same neighborhoods — and most of the time we do. (Our cultures have long been intermixed. As a child in the 1950s, I played with the children who lived in the black neighborhood across the back road, listened to black singers and musicians on the radio, and with the integration of major sports, rooted for black athletes.)
A peaceful association isn’t easy to preserve, though, when you have a race industry working full time inciting hatred against whites — and a government and mainstream media that act as accomplices. (BlackLivesMatter was founded on lies -— publicly exposed lies — about what happened in the Ferguson shooting, yet most of the American people still don’t know it.)
And yet what are we doing today? Importing cheap labor that is incompatible with our culture, we haven't learned a damned thing.