The left/right divide in American politics is a myth. Clinton and Harris are both establishment candidates. The only establishment candidate to have won a presidential election since George Bush Sr. in 1988 is Biden. And that was only because of Trump's first term, and he was losing his election before bowing out.

The Democratic Party has been putting forward establishment candidates since at least Jimmy Carter, the only exceptions being Bill Clinton and Obama. And notably, they both were, like Trump, a bit of a black swan in party politics.