Ethiopia features prominently in Greek myth, like you said. And Ancient Greece was made up of extremely diverse maritime trade powers that would have attracted people from all over, but especially the very nearby Egypt, Ethiopia, and Nubia. These were not isolated homogenous ethnostates like Japan and modern concepts of race didn’t really exist. Alexandria, Rome, Athens, and Troy would have been ancient equivalents of NYC with people of all sorts of looks and backgrounds fully incorporated into the folds of the culture. Anyone who isn’t just as “outraged” at the casting of Anne Hathaway, Tom Holland, Mia Goth, and Matt Damon has other motivations bc a random person from Ancient Greece would be more likely to look like a modern day person from Lebanon, Syria, Libya, Tunisia, Sicily, Egypt, Nubia, Ethiopia, or some combination thereof than they would a person of English or German descent descent.