Your absolutely right. The assertion that our revolution was to protect slavery is not supported by the writings and speeches of our founding fathers. The founding fathers didnt start slavery in America, they found it here.
Thomas Jefferson, and most of the founding fathers, realized slavery was incompatible with our declarations founding ideology, all men are created equal.... They expressed many times in their writings that they wanted to see slavery end and some even joined abolitionist organizations.
The father of our nation himself said this;
I can only say that there is not a man living who wishes more sincerely than I do to see a plan adopted for the abolition of slavery.
George Washington letter to Robert Morris 12 April 1786
While keeping over 200 slaves and not freeing them.
Actions speak louder than words.
London had already issued two emancipation proclamations that would have freed Washington’s slaves years before that.