The casting would be fine if it was a radio drama.
A movie is an immersive visual attempt to place you at that place and time even if it’s fiction.
And sometimes a movie is agitprop...
That's one problem - if you're trying to recreate the ancient Greece of myth casting a Nigerian as a Greek just doesn't seem plausible. It would be like trying to make a movie set during the Vietnam War and filming it in Arizona with saguaro cactus and ocotillo in the background.
Problem number two, the bigger one, is that this type of casting is done for the sake of promoting DEI and the cult of "diversity".
When people see it and come out after being immersed they will love it
That’s my prediction based on my knowledge of Chris Nolan fans, Chris Nolan’s expertise as a director and his wife’s expertise as a producer as well as Chris Nolan’s education in and understanding of literature and story telling
That’s the truth.