I disagree with your terminology. Democrats fought for slavery (against Lincoln and the Republicans).
Democrats then passed Jim Crow, and fought to keep blacks down.
Democrats then got shaken up by the 60s Civil Rights movement. Albert Arnold Gore Sr (D-TN) was the loudest voice of those opposing the 1964 Civil Rights Act... but then they quickly started supporting Affirmative Action and racial preferences in college admissions and a zillion other areas of life.
They aren't the Party of Slavery, they are the Party of Racial Division and Disparity (and dedicated to keeping blacks on their plantations). In all cases, and since their inception, Dems have fought to keep races treated differently, and the GOP simply wants people treated equally, by the content of their character and not the color of their skin. This is the one consistent feature for both parties.
Nope - Party of Slavery.
On the plantations of the antebellum South, they used people of African ancestry to convert cotton seeds into cotton bales for the benefit of the Democrats who controlled local society.
In the modern era, the Democrat descendants of those original Democrats still use people of African ancestry on big-city urban plantations to convert (other people’s) dollars to votes for the benefits of the Democrats who control local (and now national) society.