First black slave in what was to become the USA, was Esteban the Moor. Shipwrecked off Florida in 1527 on the Spanish Narváez expedition, he was with Cabeza de Vaca in their trek and subsequent enslavement by various Indian tribes, to Texas.
Later, freed from Indian slavery by the Spanish he accompanied Frey Marco de Niza back into New Mexico where he offended the Indians and was killed.
I saw Henry Louis Gates on TV once talking about Esteban in glowing terms as if he had been the leader of the expedition.