"Ripping off Cuphead" is an odd thing to complain about, when Cuphead took its art style from Fleischer Studios and early Disney, and its music from Cab Calloway
Then there's the fact that that the character designs and animation Cuphead took from were often quite overtly racist, and in tweaking them just enough to put in the game, Cuphead whitewashed that.
But that's an essay someone else has already written: https://unwinnable.com/2017/11/10/cuphead-and-the-racist-spectre-of-fleischer-animation/
Cuphead itself shamelessly rips off other works, is what I'm saying. Really, really shamelessly. To a degree that's less charming than uncomfortable. So if another game wants to rip them off, fine.