set back the global movement towards liberation and socialism back by a 100 years.

roughly 2070s? god i hope not. i don't think we're going to make it that long into climate hell under the current system

I think you could make an argument for Jefferson, given how the Louisiana Purchase set the stage for a lot of the subsequent expansion and genocide. It's probably inevitable that America would expand to some degree, but it could have been slower if they didn't make the purchase, possibly resulting in a smaller and less powerful America.

Of course, there's also the part where he owned slaves and upheld slavery.