OK, time for some common-sense...
Well, why should we start that now?
So when we're talking about Mary Sue, it's a matter of degree, and Rey, in comparison to Luke, merely coasts her way through obstacles in The Force Awakens. This is mostly JJs fault as he did much the same thing with Pine's Kirk. Kirk was "destined" to captain the Enterprise and so the first Trek film sort of ushered him to the captain's chair ridiculously fast. He sort of mis-reads the whole "chosen one" thing to the level where the movie feels like watching a videogame on easy-mode.
The point that has been made here is that there's hypocrisy around the idea that Rey is a Mary Sue when Luke isn't. Sorry, but if you're going to use that moniker on one, you have to put it on both, particularly during ANH for Luke. Using common sense (

), there is no way that Luke can do what he does with his level of knowledge, experience, PTSD from losing his aunt, uncle and mentor in the course of a day. The man would be on the floor in a puddle, not saving the Rebel Alliance. Yes, Rey is in the same boat. I will admit that. So, when you make the reference to the hero’s journey (which can be applied to Luke OR Rey), yes, shortcuts are taken in
both stories. We’ve been over that in this thread.
We also live in a world where we have shorter attention spans than we did 40 years ago. If we’re talking about a franchise where much of these things are already spelled out for us, we don’t need it spelled out again. There is enough evidence presented in TFA for me (and others) to accept that Rey can do the things she does. Combat. Check. She’s learned hand to hand regarding defense on Jakku. Pilot. She says she’s a pilot. (So did Luke, so don’t give me any of that.) The only questionable things she does is the mind trick and pulling the lightsaber. At this point, though, something awoke in her. She touched the lightsaber and everything changed. She even admits to Finn that even if she told him how she escaped on Starkiller, he wouldn’t believe her. She’s incredulous over it. There’s something more to Rey. We know that. There's more to this story that the film seems to be asking, not like it "asked" about Snoke, not like it "asked" about Rey's parents, but a real, honest to God mystery around Rey. If that makes her a Mary Sue, fine, but Luke pulled some miracles out of his ass too. We can't ignore that.