So if someone asked if that line from Soul is "racist", it depends on what definition you are referring to. Yes the line discriminates based on race. But, keeping cultural contexts in mind, does the line exploit power imbalances in our society against white people to denigrate them? I think a lot of people would say no.
I know times change, but when I was a kid, it was okay to make racist jokes as long as it was not mean spirited. We joked about all races, but the point was alway that it was a joke, similar to jokes of stereotypes about other characteristics of people.
Edit: Then again, I acknowledge that language/culture are in constant flux, and maybe I should use “racial joke” instead of “racist joke” if I want to convey my thoughts to the largest number of people and have them interpret it properly? Or it can be accompanied by paragraphs of explanations.
By this reasoning, minstrel shows are not racist, because the culture at the time did not see it that way.