When JetFire told the humans the story about the Primes that they sacrificed themselves to protect The Matrix Of Leadership, was Sentinel Prime one of them? Since he's a Prime, just asking.

What he said. And Sentinel couldn't have sacrificed himself with the other Primes, as that would have meant he could not be commanding the Ark. Instead, his body would have been in the Tomb Sam and co. found in ROTF.

He means the first Seven Primes, Seven of the Original Thirteen. Prima, Vector Prime, Solus Prime, Nexus Prime and two others hid the Matrix from Megatronus "the Fallen" Prime.

I didn't think the Primes story was handled that well in the film. The comic/novel version where The Fallen slaughters almost all of them & the last one builds the tomb makes more sense in my mind.

This makes tons more sense, because I just can't see how Optimus Prime+Jetfire's parts is more powerful than 6 ORIGINAL Primes vs the Fallen

When the Megatronus Prime betrayed the other Primes it seemed at a time before there was war on Cybertron. Optimus Prime was involved in countless stellar cycles of war, the Fallen seemed more behind the scenes, issuing commands he wouldn't undertake himself, possibly even doubting his ability to combat countless Autobots