You're right about her support, but white progressives are generally the biggest advocates of Diversity. IME minority groups are generally more conservative than progressives are (though of course we're talking about tens of millions of people each with their own opinions) and care about how they are treated but less about Diversity as a solution, but of course most won't consider Republicans for obvious reasons.
> white progressives are generally the biggest advocates of diversity. IME minority groups are generally more conservative than progressives
I think you're correct about all that. But you overlook that minority groups care about "diversity" for other, different reasons. Generally speaking, minority groups care about it as a show of commitment to their group. Jim Clyburn was instrumental in Harris's nomination. He isn't a progressive. But he cares a lot that the party appoints black people to key positions.
That's just how the party has long worked. For decades, Catholic immigrants voted for Democrats as a bloc and in return Democrats delivered political benefits to Catholics and appointed Catholics to key positions. Minority groups today aren't any different. Myriad ethnic activist groups are in different communities--Muslims in Queens, Latinos in Nevada, etc.--mobilizing those communities to vote Democrat. And those organizations deeply care about the party delivering key appointments to members of their group.
So you're correct that Elizabeth Warren was the candidate favored by progressives who value diversity as an abstract ideological principle. But she was not favored by the groups that help deliver actual votes from minority voters and wanted the appointment of someone from their group in return for that support.
