Virtually all of the British colonists, whether in the US or the Caribbean, were slave traders. And they traded in both African and American Indian slaves.
The Spanish colony of St Augustine (now known as Florida) permitted the African slaves of the English colonies to the north (Georgia and the Carolinas) to gain their freedom if they could get across the Florida border. They had to accept Christianity, swear allegiance to the Spanish Crown, and start learning Spanish.
This ended in the 19th century, when the pressure from the formerly British American colonies made it too dangerous for the Spanish to continue this policy.
Also, when the British destroyed the Florida mission chain in 1702-1704, some 11,000 Indians were captured and sent to the British Caribbean to be slaves on the sugar plantations.
Slavery was practiced in the Spanish colonies, but it was more like indentured servitude: slaves could earn money, buy their freedom, be freed by their masters (something not permitted in much of the South), had to be permitted to receive the sacraments of the Church (evangelization was actually forbidden in much of the non-Spanish South, and there were jail terms for the Protestant ministers who tried it), and marriages had to be respected.
The Spanish had been forbidden by the Pope and Queen Isabella to enslave the Indians, and Columbus actually went to jail for bringing back a few Indians to show off at court. Naturally, in the Spanish colonies, the Franciscan mssionaries and the Spanish governors had to fight constantly against the “property developers,” as we would call them now, who attempted to enslave the Indians in one form or another. And sometimes the missionaries had to fight against the governor.
But chattel slavery was not practiced in the Spanish colonies, while it was the norm in the British colonies.
Brazil, btw, being a Portuguese colony, was a separate case, because the Treaty of Tordesillas gave both Africa and Brazil to the Portuguese. They completely ignored the papal bull forbidding the enslavement of the native peoples and started buying slaves from the Arabs in Africa, since Portugal had been given the “rights” to Africa.
The British-American colonists were really the big US slavers in Africa, buying the slaves from the Arabs and shipping them to the US. The major Spanish participation was with the ships, and the “Amistad” (upon which the movie was based) was one of the ships that a Spanish captain had leased out for the transportation of slaves to New England. Being a Spaniard, he didn’t keep them chained up in the hold, he let them up on deck...and the rest is history.
Interesting that they didn’t look into the backgrounds of Presidents from former slave states, like Johnson, Clinton or Carter.