Conservatives are no longer conserving the rate of change to human and social values traditional to the United States.
Under Trump they have become fully reactionary against anything outside of their wealth and privilege bubble.
So what Harris has done has pointed out that the GOP are not "normal" because their values are really really really far outside the norm.
Harris flipped it. Because it is true. And she is a better politician than Trump. Poor Vance, not having an ideological raft to believe in, can only say reactionary things.
Don't buy their propaganda. They didn't become this under Trump. They have always been the protectors of wealth and privelige. You can trace that history right back to the birth of Conservativism in post-revolution France. This is just the latest incarnation.
I highly, highly recommend Corey Robin's book The Reactionary Mind. He breaks down the whole history of Conservativism in a very accessible manner, and shows how every incarnation of the movement has ultimately been about one thing and one thing only; preventing the enfranchisement of the disenfranchised.
This seems like a good spot to recommend Roberts Evans Behind the Bastards: How Conservatism Won. in which "Robert sits down with David Bell to discuss how a consortium of rich failsons got together to fund a network of right wing think tanks and shift American culture in a fun new direction. (note: it was not actually fun at all)." It's a bit long but is very informative.
tl;dr the rich hated FDRs New Deal and immediately set about undoing everything it touched, they want a return to the gilded age with themselves as the robber barons and gentry and everyone else as a subservient underclass