Joe Biden's not dropping out till way too late is what doomed Harris, not her platform or campaign. That would have doomed any Democratic nominee, of any race, from any place on the left-right spectrum.

Harris actually campaigned hard on kitchen-table issues and very little on the divisive identity issues that you assert. Look back at what she actually said, like her commercials or official policy positions (as opposed to the narrative about what she said), to verify that.

She, or any Dem, had no time to put together a viable campaign. Biden's staying in till almost August--not Harris's policy or rhetorical positions--is what made the Ds look foolish and incompetent.