Well, first off, we do need prosecutors, right? We can agree that when someone murders a person there should be legal recourse, correct? So the issue is not blaming her for being a prosecutor but judging her on the type of prosecutor she was.
She did a lot of good in that role, so don't consider this the definitive list, but she:
- ended the practice of charging underage girls with prostitution
- she made a campaign promise not to use the death penalty and kept to it (even when facing intense criticism for it during a case where a man killed an on-duty police officer)
- she launched "Back on Track"
(BOT), a reentry initiative aimed at reducing recidivism among low-level drug-trafficking
defendants
I'm going to assume your comment about her "incarcerating Black people" might have something to do with the lie being pushed online saying that she incarcerated thousands of Black people for marijuana charges. During her six years as San Francisco DA, her office sent 45 people to marijuana related offenses, total--of all races.
If that wasn't your gripe, then you're going to have to be more specific. Prosecutors put people in jail; it's what they do. It's a necessary role in society as it currently operates. Unless you're just saying you're anti-prosecutor altogether, which is ridiculous, I'm not sure what the complaint here is.