Halle Bailey has been cast as Ariel in the live-action remake of The Little Mermaid. A casting that has proved to be controversial.
In the original animated movie, Ariel was white. However, Disney has cast a black girl in the lead role for the live-action remake.
Most people don’t have strong feelings either way. Ariel was white and now she’s black. Which, for a fictional character, is absolutely fine.
However, as usual, there are people on both sides arguing from extreme viewpoints. Personally, I think any actor should be able to play any fictional character. Including The Little Mermaid.