That's like the only non-Mary Sue moment, when Kylo easily restrains her. That's not the part I have a problem with, so I find it funny that you are explaining that part away. Kylo should be able to easily restrain a non-forced trained opponent. It's her beating his mind probe right after that is problematic.
Being a scavenger doesn't make you good at fixing or building things. It means you are good at finding stuff and taking stuff apart. Han and Chewie are smugglers with decades of experience repairing that very old ship that continually breaks. And she's not only better than Han and Chewie, she's better then the engineers who built the Falcon. "What'd you do?". "I bypassed the compressor". So Rey rips out the compressor and wiring to fix the Falcon, 'cause apparently it's not needed. Stupid engineers. Where was Rey when they designed the Falcon, she could have really helped.
I didn't say she easily defeated Kylo. I talked about her being an expert staff fighter. Something she never earns. She easily knocks out two assailants, then easily defeats a life-long trained storm trooper (Finn). In the next movie, she easily defeats a Jedi Master.