If I was to say, yes. This is an opinion from someone that isn't even from the US, mind you, but given what I know about the constitution I do think it was the case.

To this day, we generally don't allow people to vote in an election if they aren't a citizen yet I reckon we don't consider non-citizens lesser human beings. The idea of allowing only those with property to vote (because they have stake in the country) or to only allow men (they will be fighting the wars) are outdated, but they aren't nonsensical.

I think like half of them did. The compromise over slavery cursed our nation.

You're being too reductive. There is no simple one sentence answer and the path to modern western liberal values spans 400-ish years.

It wasn't really that long ago that all/most societies believed that slavery was normal.

Just the IDEA that "all men are created equal" is intensely liberal. And that it was put into a document without qualifiers is miraculous. We can't judge the past only from a modern lens. YOU didn't do anything to help the world move towards liberal values. YOU are just the benefactor of thousands of years of conflict/learning/etc.