The idea is that she’s black and will attract votes. Beyond that...she’s worthless, and comes across as a very hostile person.
Harris is not really black, most of her color comes from her Indian mother, her Jamaican father is almost as white as I am.
Both of her parents were foreign nationals, she is not a natural born citizen.
She underperformed because blacks know she has no street cred; if she is on a ticket as VP, it is to attract white liberals.