Try replacing a movie about Harriet Tubman with a white woman or MLK with a white man and see what happens.
Mickey Rooney as the Japanese caricature in Breakfast at Tiffany's
Better was Othello with Laurence Olivier as a "Moor"
Though in BOTH these cases, these were fictional characters - just like Ariel (the little mermaid) or the MCU Heimdall - so fine
Oh and for the MCU - we have white actors playing Brown or Asian characters like Wanda Maximmoff and the Ancient One
BAD was "Anna and the King of Siam" - where Yul Brynner or Rex Harrison played Mon-Thai kings
BAD: the "Gods of Egypt" which was complete white-washing of Egyptians
Worst: John Wayne as Genghis Khan - he didn't even attempt to be like Chingiz! Temüjin