Oh please. Do me a favor and go rewatch TOS S2 "The Deadly Years" or hell the TNG feature film "Generations"; and get back to me on how Starfleet never puts green Captains in command of major Federation starships.
Yup! -- Deadly Years, emergency situation (dying, incapacitated real Captain); the writers telegraph it is wrong, but it's an emergency situation and the guy is a ?Commodore, whatever, has the rank. And we see how dumb it was for him to be in the seat. Moral: don't put unproven people (e.g. Tilly) in the big chair.
GEN, emergency situation again, right? Where Deanna, who is not an ensign (i.e. newb) and has gone through command school, I think?, gets the big chair, and keeps everyone alive somehow? (I'm not a TNG fan, so isn't this the one where people make the sexist women-driver joke?
BUT
Saru chose -- in a NON-emergency situation, weeks ago -- a neurotic Ensign (which rank equals "fresh outta Academy") with no command experience, who generally does science stuff -- to be his second in command. Egregiously negligent. As we saw. And all her underlings with more experience just smile at her and think it's cute when she is being incompetent.
(Surprised you didn't quote ST 09 Kirk in the big chair. That was dumb too.)
And of course I must be sexist to criticize the woman commander, let's go there, right? Except, I think it should have been Nillson or Ouwo. Reno woulda at least been more entertaining in the cringey banter.