He needs to be black due to reference to it in the lines. These words, and all references to the Moor, could of course of removed.and Othello doesn't need to be black at all, it would make it about the jealousy.
Also, the rest of the cast don't need to be white, and they haven't been, without it affecting the story.
In a real colour-blind casting situation, you can absolutely have a white Othello if you want. That's the whole point of it, you rely on the text, the lines, to tell the audience what they need to know.
If you want the text to match the racial profile of the characters, then you need most of them besides Othello to be white, particularly Iago and Desdemona and her family, but most of the others as well. Othello is meant to be in a context where his blackness is unusual and unique - that's what causes the problem, it's what makes him the way he is, it's part of what fuels Iago's hatred.
Colour-blind casting isn't just meant to be about opening up roles to more performers - it's also about how the text of the play is related to the depiction of the play, how much they ned to "match". If the play isn't being presented in a naturalistic way, you could have complete freedom with your casting. It's a bit like abstract painting.
This is what's kind of frustrating about these conversations, and what you see with the casting - people talk about colour-blind casting but they clearly don't really mean that it's colour blind in the real sense. Only that they are wanting to include "diversity" where it seems less likely to interfere with the believability of the role. So - not colour-blind at all, actually.
At one time this was typically handled by making up the actors to fit the role better. Part of the reason colour-blind casting has been popularised is that is now taboo, so if your actors don't fit (which is common in local theatre) you can just say you are not casting based on race/ethnicity.