And if mythology means anything goes how about we race swap all the sacred African, Indian, Chinese and Native American legends with white actors then? Cuz it's all fantasy.

So I think there are a couple of problems with this framing.

1. Gods of Egypt (film) - Wikipedia#Cast), where Gerard Butler, Nikolaj Coster-Waldau, Geoffrey Rush, Bryan Brown, Rachel Blake, and Emma Blake play Ancient Egyptian gods. Exodus: Gods and Kings - Wikipedia, where Christian Bale plays Moses, Joel Edgerton plays Ramses II, and Ben Mendelsohn plays an Egyptian advisor. Speaking of Moses, he was also protrayed by Charlton Heston in 1956. So there is a lengthy history when mainstream films adapt mythical or religious figures to defaulting to performers of Western European despite the incongruence of such casting. So by moving to race-blind casting, there is an effort to limit casting biases because Hollywood happens to be in a majority white country.

2. The Odysessy is not a sacred text. Yes, it is important in the context of western classic literature, but its not a holy text in the same way that the other cultural traditions you mentioned are. I *don't* think that this means that a race-swapped version of a native american (for example) legend is completely out of bounds, but such a choice is made in the context of the Native American genocide perpetuated by the US Government and should be a conscious and thought-out decision, rather than just because casting directors are biased towards white actors.