“People know” comments, such as the one in this article are increasingly annoying. Mainly, because they are simply wrong.

No, we don’t know that Ortegas and La’an aren’t on the ship in the first year of Kirk’s command.

Sulu was a xenobiologist at the beginning of TOS, and Kirk had already been captain for some time. There was a bit of a rotation of pilots in the initial episodes.

TOS didn’t even have a regular security officer.