tl;dr: Cuphead is racist because racist stuff happened in the 1930s and the devs didn't insert social commentary into a game about a fucking anthropomorphic cup.
I'll never understand this concept. When I eat a kebab I don't reflect on the Armenian Genocide and if I watch a Samurai movie I don't ponder the Rape of Nanking. Why would I play a cutsie cartoon styled game and think about Jim Crow?
Every time I eat sausage, I cry six gorillion tears for the Jews turned into soap by Hitler. I can't even smoke a cigarette without shedding a single tear for the bajillion Native Americans genocided by the evil white man.