Hmm…I think that, in some ways, the ‘magical negro’ trope isn’t so much the result of stereoyping, btu the inevitable result of POC being cast in supporting roles.
In most story structures, every event relates back to the main character and the main plot. Other characters are defined by their relation to the protagonist: the love interest, the mentor, the rival, the best friend. This is unavoidable. Good writers should create characters that are rich and complex, but a secondary character can’t go off and do their own thing in the middle of the protagonist’s story. Their motivations, goals, etc. must be played down for the sake of keeping focus. Their relationship to the protagonist will almost always be their most important relationship.
So, what do you do if you want to add a black character to a story for ‘diversity’, but you don’t want to make them the main character or love interest? And you don’t want to make them the antagonist, either, because you don’t want to be racist? You shove them into the role of helper to the white protagonist, like the sassy black girlfriend, or the wise black mentor.
In my view, the problem isn’t that there is something inherently wrong with a black secondary character existing to aide a white protagonist. Many if not most secondary characters who are ‘good’ earn their place in the plot through assisting the protagonist and existing as a foil for the primary story line. The problem is that black characters are constantly thrown into these roles for the sake of ‘diversity’, but rarely get their own stories, where, perhaps, a white person is playing the wise mentor or best friend They’re always assigned to the secondary, support position.
bolded for emphasis