The foundational idea of America which appeals most to me is not that of liberty. Liberty is a means to an end. The end is perfectability, progress.
What liberty enables is correction, learning. It enables self organizing systems to organize. Tyranny prevents this.
Our early Presidents were slave owners. I think even Adams owned a slave at one point, although if memory serves he freed him. But our system organized morally. We fought a war in which some 650,000 Americans died, and a multiple of that lived with physical and emotional wounds for the rest of their lives, in no small measure so that slavery would be ended. Saving the Union was the stated goal, but the Union would not have needed saving had the Republicans not brought the issue of slavery to the fore, frightening Southerners.
This notion of perfectability is the entire reason that political regressives have been able to get traction by calling themselves “progressives”. The basic idea is already in our genes, which tend naturally towards idealism.
I believe strongly that Americans are basically decent people, who are simply starved in our disinformation age for accurate and contextualized facts. Give them the facts, and they will make the right decisions.