Stargate is really Teal'c's story.
In CotG all the characters are (re)introduced, but who gets the most drynamic intro? Teal'c. Of everyone whose lives are changed as a result of the events in that ep, Teal'c is the one who has to completely re-assess his life, turn it around and make a whole new place for himself in the universe.
The arc that encompasses all seven series of Stargate is the struggle against the goa'uld. Who more than Teal'c is personally invested in that fight?
Teal'c might stay in the background rather more than he should, after all, proper heroes are frequently the modest type. But Jack is only the leader of SG-1 by default because Teal'c (and Daniel) hasn't usually decided to argue with him, disregard what he says, or generally take over. Jack is, of course, Teal'c's Apprentice (That got said on the show, so IT'S CANON )
And Changeling is definitely the best ever episode of Stargate. And Threshold was great too. Those few, precious eps which showcase Teal'c's journey just *have* to be leading to some big ending for him, where he gets to free the Jaffa / defeat the system lords / something v important in that vein.
Yup, it's all about Teal'c. I'm in the Happy Place.