Thanks for your new quotes, I've added them to my collection of Founders' anti-slavery quotes.
Your Jay quote I had already, plus other quotes from Washington, Adams & Patrick Henry.
Indeed, the key point to remember here is that neither I nor anybody else has ever found a Founder's quote to the effect that slavery was a good thing and should be both preserved and expanded.
At best (or worst) our Founders believed slavery was a necessary evil which should be abolished wherever and whenever possible.
ProgressingAmerica: "Our country did not fail on race, not during the founding.
That was forced on us prior to independence and gained new life thanks to Eli Whitney."
Well... the question you raise here is whether slavery was a flaw in our Constitution or a feature of it?
The answer is, slavery was not just a flaw, rather, it was an essential feature, arguably the most essential feature, because, had the Founders not agreed to it, then there would be no United States.
Slave-states would have refused to ratify in 1788 and the Constitution would have failed ratification by 3/4 of states.
How long the old Articles of Confederation would have lasted after that is anybody's guess.
Gradual abolition was also one of our Founders' original intentions and it was well under way in 1787.
Our Founders had reasons to believe that abolition would be eventually accomplished, state by state, working from North to South.
That original plan was not fully abandoned until the Founding generation was gone and abolition failed in Virginia, circa 1835.
Only then did pro-slavery politicians begin to argue full-throated that slavery was a positive good thing that should be preserved and expanded as much as possible.