I think it's wrong to say that just because the captain, as a character, is listed first in the credits it automatically means the show is about the captain, and the rest of the characters are only sidekicks.... The Trek shows are not about captains and their underlings, they are about a group of people.
Exactly. Sisko was listed first in DS9's credits, but there were plenty of episodes that he was barely in. All the modern Trek shows have been intended as ensemble shows, although ENT ended up being less so than its predecessors. The captain (or commander, in early DS9) was the central character, the anchor of the ensemble, but the shows were never built entirely
around their captains. The only Trek series that was meant to be centered overwhelmingly on its captain was TOS, and that didn't work out because Spock was the breakout character and Kirk ended up having to ride his