>>45365020A big reason why "blackface" has that emphasis on the mouth is because some black people do actually have very light lips compared to their skin. They weren't making up traits for black people to be offended by, they were emphasizing existing ones.
Cartoons are all about emphasizing and/or simplifying familiars features to make up for the fact that people have to connect with 2D drawings. Even "realistic" art styles like King of the Hill have exaggerated facial proportions like Hank Hill's forehead, even though you feel like you know you've seen someone who looks like him.
Denying that black people are capable of having pink lips because of racists before is like denying they can also have light-colored palms and just resorts to people never actually looking at a black person when they draw them, which results in people having to make fucking art tutorials on, "How to draw black people" or "How to put lighting on black skin" because people want to pretend there are no feature differences and that we're all the same under a rainbow.