Biden was more "new dealy" and won. Harris had nothing of the sort to sell and lost. I'm not saying Obama's skin color isn't a factor in our politics since 2008 but it's not the Rosetta Stone.
And she's a woman and she's black, again. Then there was the issue that one side of the Democratic party wanted to support Israel more strongly or something, and the other side wanted to protect gazaans and the Palestinians. I think many people wanted to do both at the same time, but there is a fair number of people that picked one side or another. Some of those people voted against her. Some people in my family thought the biggest problem facing America was dei.