I'd watch a series with a captain that bullshits themselves through. Not a stupid captain, the opposite: every intelligent, but heavily lacking knowledge. So they have to navigate smartly through every interaction and fake it until they make it.
The captains shown in Star Trek wouldn't even need to be knowledgeable of all of these weird space phenomena. They have their science officers and general advisors they can ask "What are our options". They're just good managers, essentially
Also bonus points if the captain actually improves the situation via their lack of training.
For example encountering a race who insults one of their crew, normal starfleet captain would brush it off but fake starfleet captain challenges them to a fist fight.
Turns out the aliens greatly respect such actions and starts off first contact with a gesture of equal respect.
I'm not well versed but Caiphas Cain from Warhammer 40K was supposed to be a big fraud that just happens to have a maxed out Luck score? Something like that would be fun lol
The man held out against an admitedly injuried Khornate berserker, he's just got a healthy sense of self preservation and a cripling case of imposter syndrome.
Captain Ross, a former Indiana Jones type explorer who's taken over the identity of her dead twin sister after a tragic accident, to escape the Orion syndicate.