Rights, in the way our founders saw them, were natural or god given. IF that is the case, when the founders denied rights to blacks they were violating natural, or god's law. It cannot apply to all humans and then you decide that some humans are less than human without violating natural law. Just because you possess a myopic racist view of what constitutes a human does not make you right. That white people viewed black people as less than human is NO LESS wrong than the Nazi's viewing Jews as less than human.
Hold on... I am not arguing it was MY viewpoint that blacks were sub-human, that WAS the prevailing viewpoint of the time. I'm not saying it was right, it obviously wasn't right, we changed the law, we freed the slaves, we passed Civil Rights. The whole entire basis for us being able to change, was the Constitution, and that very moral foundation. But even the perception of blacks in 1865, were not the same as in 1776. At that time, black slaves were akin to cattle, as far as the founders were concerned, some of them even owned slaves.
It's not a "myopic racist view" at all, it was just the way people thought back then. You are trying to apply a modern enlightened and educated viewpoint, where it
did not exist. In the colonies at the time, there were only a small handful of people, mostly Quakers, who saw the African slave as anything more than a dumb animal. They 'looked' like people, but they weren't considered part of our species. It wasn't a 'racist' view, it was a complete misunderstanding that we belonged to the same species. Over time, this 'belief' changed, but we can't apply current truths where past beliefs existed, it's intellectually dishonest to do so. We can say they were wrong, and they should have understood what we understand today, but we can't condemn them for what virtually everyone believed at the time.
I've made the comparisons before, to the unborn fetus. Currently, the unborn fetus doesn't have Constitutional rights... now let's say that way off in the future, the SCOTUS rules that they do have the right to live, and every other inalienable right... does that immediately condemn for all eternity, all the people who supported abortion for all those years before? Does that make them monsters and reprehensible characters, because they were 'myopic bigots' or didn't see the truth? I think it is always important to evaluate things in context of the times, and what the prevailing thoughts were then, not what they are now.
The more important thing here, is that we corrected the problem through the very fundamentals of our Constitution. It was so brilliantly written as to allow emancipation, and secure the blessings of liberty for the slaves, and civil rights for their ancestors. The previous system, which relied on rights dictated by the King, may never have accomplished this. It would have been up to the King whether slaves would be free. Considering England was the primary beneficiaries of southern-grown cotton, this would have been highly unlikely.