We also saw Asian, Black, Indian and Latin Starfleet officers during TOS.
But with a majority of WASPy characters. We have Uhura, Chekov and Sulu, but the typical redshirt's name beging with O' or finish with son.
Kirk and Scott were played by Canadian actors.
You don't need a Danish actor to play Hamlet or an Italian for Romeo Montaigu.

Patrick Stewart is from England and played a "French" captain. (John Cleese made a better French dude.

)
Scotty seems to be the only anglophone whose not from USA and I think it was still usual to met Scottish immigrants (and not simply of Scottish descent) in North-America in the 60's.
Shatner and Nimoy are both jewish and portrayed WASPy characters (Grayson sounds pretty Anglo-Saxon).
We also see an Indian Starship captain (with an accent) ...
And he was male.
Take a look of senior officers introduced in the first three movies:
- TMP, Admiral Nogura (it sounds Japanese, but we don't see him) and Captain Decker, a white American.
- Captain Terrell, black, but American
- Admiral Morrows, black, but American, Captain Styles and Captain J.T. Esteban, spanish family name, but American accent and anglo-saxon initials
I'm not seeking for racism, I'm pretty sure it was absolutely not the case. For me, what we see in STIV is the start of an adjustment that really became effective with TNG and following series. This adjustment it's not into the Star Trek universe, but outside, into scripting and casting.
and many aliens Starfleet officers.
And how many of
them were female ship captains?
And how many aliens neither Vulcans nor Klingons did we see in first three movies? Not a lot. Of course, there was logistical reasons, but what whe see in STIV is also a part of this adjustment.
There's nothing in TNG that suggests there had been a drop and a new rise about gender equality during TOS era. Star Trek has a naive conception of progress. There had a third World War and after that, it's the come-back of a linear progress.