The nation was founded with and built on an economic system whereby enslaved, unpaid Black labor made white owners wealthy.
Jefferson's Declaration of Independence was based on equality--equality of all white male property owners.
Those are both true. The More Perfect phrase meant equality would expand to all of us (over the loud and now violent objections of predominantly white men).
When the Republican AGs whine that "public schools should not be given grant funds to teach about critical race theory, “including any projects that characterize the United States as irredeemably racist or founded on principles of racism (as opposed to principles of equality)" they're not whining about how women wrote themselves into the Constitution, oh wait, they didn't, or Black men writing for all the world to see that they are worth more than white men.
That 3/5 clause is a tricky one, isn't it. Hard to argue it didn't reference white supremacy, isn't it? That women didn't achieve the franchise until 1920 doesn't speak well for White men in power, either.
There is one demographic group who set themselves up as superior legally and constitutionally. One. That group doesn't want to let go of their power and position, nor do they want to acknowledge other's equality, not really. If they did, we'd not be refighting the same race and gender wars over and over and over.
They're not objecting to the practice of slavery, just teaching about it.