Read Sen. Mike Lee’s book to see what some of the other Founders thought. A very good read and some surprises. Also touches on why the EC came to be.
As an indentured apprentice to his brother, Ben was for all intents and purposes a slave in the latter’s Boston printing business. He must have eventually made the connection and realized any non-penal forced servitude was immoral and indefensible.
The truth is Ben Franklin’s got a mixed history. Its true he went from slave owner to public abolitionist.
It is also true that he derived considerable revenue/profit from selling advertising to slave traders and to slave owners looking to recapture escaped slaves in his newspapers. He was never averse to making money from slavery whatever his public statements about it.