I agree with most of what you stated, but this is not entirely true. But, even for the sake of argument, what "challenge" did Luke really go through in the OT, in the first movie. Honestly, of the "main" protagonists in each trilogy, only Anakin really faced challenges in all his movies.
Luke manages to outfly trained military pilots, even when he does a stupid maneuver that should have got him killed. He lost his Uncle and Aunt, but in the next scene goes "there is nothing for here for me now" like the deaths of the people who were basically his parents meant NOTHING. He cried more for Kenobi than them. Luke doesn't really face a challenge, he manages to blunder his way through the movie.
The complaints on Rey can apply to Luke if you simplify everything to make the argument. It's Star Wars, the heroes typically have plot armor. I don't get why Rey having it is suddenly a problem.