At the time of the civil war the Republican Party was the ABOLITIONIST Party. There were Democrats north and south, but Republicans were uniformly ABOLITIONIST, and the Negroes who could vote after the war voted Republican even more uniformly than they vote Democrat now. They changed parties (to align with the KKK) during the Roosevelt years, when they perceived that the New Deal was a better deal for Negroes. In the 1960's, 70's and 80's white Democrats in the South saw that their party was moving further and further away from the philosophy of their forbears (States' rights), and they gradually moved to the Republican Party, where they now generally reside.
As for any race being "superior," that depends on the characteristic being measured. When you are basing it on IQ, then clearly. American Blacks are, on average, substantially less intelligent than the norm (85 vs. 100). Asians are higher than the norm, and Ashkenazi Jews, the highest single demographic.
But if there were a basketball game pitting five randomly-selected Black men against five randomly-selected Asians and Ashkenazi Jews, I'd bet on the colored guys.