https://www.britannica.com/topic/The-Founding-Fathers-and-Slavery-1269536
Under the Articles of Confederation, which only lasted eight yers, they banned importation of slaves. So immediately after the country was formed, a majority started the process of dismantling the institution.
John Jay was a large slave owner. Owning of slaves does not mean you support slavery, it meant you were wealthy, which many of them were. George Washington owned slaves, but freed them all on his death.
John Quincy Adams:
I heard someone say a while back that like 17 of the 39 signers were supporters but I don't remember the source. In any case, it was clear that the majority saw it as a moral abomination and upon creating the country, immediately went about the process of gradually ending it, which culminated in a war that killed 650,000 people.
Madison owned slaves and didn't free them. Here are some Madison quotes.
Natural Law exists across time and cultures and the Founders knew this. It's a pity so many are interested in throwing away their intellectual traditions. It's why Harvard et al produce mainly idiots.