There were thousands of black slave owners in this country. Not just whites owned slaves.
One of Alvar Nunez Cabeza de Vaca's 3 companions who survived enslavement by Texas Indians in the 16th century but eventually escaped to Mexico was a black man. He was later killed by Indians on a later exploration. Not long ago I saw a black professor (maybe Henry Louis Gates) cite this man (Estevanico) as a great black explorer of North America, as if he had been in command of the group.