I'm a bit like this, but really honestly the institution of the US wasn't all that great even in the context of ending slavery. Lincoln (and especially Johnson after) killed radical reconstruction, which was looking like it might make revolutionary change in the status of PoC. Instead they went mega-soft on former confederates, handed power pretty much right back to them, which in turn directly caused the Jim Crow era etc. I highly recommend anyone interested to read "Black Reconstruction in America" by W.E.B. DuBois
They also were still committing genocide against the indigenous peoples of America.