Winston Churchill was a raving anti-Semite,
I didn’t know that.
Thomas Jefferson owned and raped his wife’s half-sister.
I didn’t know that his wife had a half-sister that I assume was black(you say he owned her). I also didn’t know he raped anyone. Are you referring to Sally Hemings, I know about her but I didn’t realize she was Jefferson’s wife’s half sister or that Jefferson had raped her.
But people supported their causes and history still treats these people kindly because we still do.
I think the problem people on the Left have with Trump is that we thought society moved on a little bit further on racial issues than we really had, so we thought these historical examples didn’t apply to the present. Turns out, not so much.
There are slight differences, though. Trump made racism the centerpiece of his political campaign, and had no other coherent policy positions other than racism, so supporting him to advance a policy position that wasn’t inherently racist was an act of faith, rather than weighing the relative values of concrete ideals.