As for slaves, I think Garry Trudeau's "Doonesbury" did a Bicentennial era thread on a Massachusettsan neglecting to tell his slave that slavery was abolished.
Must have come across some anti Harvard/Cambridge stuff that included Affleck's ancestors while at studying at Yale.
Crispus Attucks was one of the colonists killed in the Boston Massacre. He was black or part black/part Native American, but I don’t think he was a slave. One of the militia men wounded in the battle of Lexington on April 19, 1775, was Prince Estabrook, a slave born about 1741, who was later emancipated by his owner.