> "Diversity" based on identity politics and physical characteristics (race, gender, skin color) is a left-wing position.
It's actually a centrist neoliberal capitalist position; the left-wing positions sees neoliberal identity politics and checklist-diversity catering to it as a tool of the capitalist class to distract from economic justice issues. (There are left-wing identity politics, but they aren't focussed on diversity, they are focussed on addressing the unique economic and social justice issues facing particular identity communities as well as the more general cross-cutting issues facing the working and under class as a whole.)
In the US neoliberal identity politics might seem like a relatively left-wing position only because the two major political parties consist of one that ranges from Right to Far Right and one that ranges from Center-Right neoliberal capitalist to the moderate Left of Democratic socialism, with the dominant faction being (clearly until the current election cycle, and by all indications still though less solidly now) firmly planted in the center-right neoliberal capitalist camp.