Nonsense. It had NOTHING to do with “racism” as we define it today. The reason slavery could be accepted in a nation founded on “all men are created equal” is that they (at least the majority who founded the nation) did not believe they were “men”. They believe blacks to be less than men. Now, I suppose you could make the case that that is its own form of racism, but it has nothing to do with how we use that word today. In other words, the people in those days did not hate black people simply because they were black. In fact, they did not hate them any more than they hated their mules or horses by “enslaving” them. I know that by today’s measure these are disgusting truths, but that is how people who tolerated slavery back then thought.
This is quite thoroughly disproven by the words of the Founders themselves, including those of Patrick Henry quoted upthread. Had they considered blacks to be less than men, there would have been no reason for slavery to bother them. And it most certainly did.
Most Americans didn't care much about it, and to the extent they gave it thought, disliked the institution while at the same time considering blacks inferior.
We should keep in mind that the "science" of the time pretty nearly unanimously concurred in this opinion. The only people who considered blacks fully the equals of whites were the occasional fanatical Christians who took their Bible seriously. Unfortunately, they were counter-balanced by other fanatical Christians who used other passages to "prove" that slavery was God's eternal will.
Over the course of the 19th century this consensus split. More and more in the North became opposed to slavery and especially to its spread. More and more in the South began to think of slavery as a positive good that could and must be spread over the Earth.
The first group tended, though not universally, to think of blacks as something approaching equals. The second group displaced them down the scale, to being less than men, as you say.
What you are doing here is displacing in time the attitude towards blacks common in the South of the 1850s back to the 1780s and making it the norm across the country. Which historical legerdemain Taney also tried in Dred Scott, but which was diced, sliced and dismembered in the dissenting opinions.