So lets zoom in on point 5 on your list:
> There are root causes to the disproportionate incarceration of African Americans that do not boil down to "the system is racist."
To claim that there are other root causes then systematic racism behind mass incarceration of black people, is placing a lot of heavy lifting on the other. It is reasonable to assume that a person holding this belief means “cultural” or, worse, “biological”. In either case, it is a racist view to hold. A conservative democrat can hold this belief, and many indeed do, however, they cannot claim to be leftists at that point, and most actually don’t. They may call them selves “moderate democrats” but I’ve never heard them call them selves “moderately left” (I’m willing to admit I’m wrong here if shown otherwise).
The leftist belief here is that systematic racism exists, and is the reason black people are disproportionately incarcerated. To reject this belief, isn’t a moderate version of the traditional leftist belief. It is counter to it. Therefor, if you reject the existence of systematic racism, you are not a moderate leftist, you simply aren’t a leftist.