You had about four things factually wrong in a three-sentence post, which is impressive in its own way, but should still probably be corrected.
Arguing that the 3/5 Clause called a slave 3/5 of a person is like arguing that because under the Electoral College, the vote of a California voter is 1/28th that of a Wyoming voter, then the Constitution treats Californians as 1/28th of a person. Does that sound intelligent to you? You repeated something that you heard someone who doesn't know what they're talking about say and you will keep arguing it.
Simply Google, "When did Jim Crow end," and you will see 1965.
You also don't understand the "America was built on the backs of slaves" argument, whose whole premise is that America benefitted and prospered off of slavery and we continue to benefit to this day. It's pretty difficult to defend that premise if slavery actually set back the country.
I still make that argument about your 2008 vote, and Joe Biden of 2008 or 2012 no longer exists. Others have said the same, but I frequently have to remind myself that this is the same person in 2021. His cognitive decline has been so dramatic, that he bears no resemblance to that person.
Finally, you misunderstand the meaning of "ad hominem." If I made the case that your points are invalid because you have grown bitter or because your feet stink, that would be a logical fallacy, an ad hominem. Calling you bitter, but not arguing that your points are incorrect do to these characteristics is not an ad hominem.
He stole your soul and your mind. You allowed him to do that.