I'm so glad Iron Man took a back seat to Thor

Not so sure if he was the main star. I think Iron Man might have been a little more important than him. Still, it was great seeing him at his full potential(I assume that's his full power range) and doing more for the team than Cap or Tony. He finally got the treatment he deserved. He was so underpowered in the other two Avengers movies, Ragnarok was really a great thing for this character.

Thanos is the main star.

I'd say Iron Man and Thor are pretty equal in the movie regarding screentime and protagonism.