Y'all mind if I write a bit about how Genji works and how to deal with him? There's a lot to him but the main idea is he punishes certain mistakes really hard, but if a team doesn't let that happen all he has is execute + ult.
There's some stuff I want to clean up after dinner... also feel free to let me know if there's anything you want linked in the first post in terms of resources, guides, etc.
Except we have a variety of people in here who are higher ranks who are telling you as it is, I'd take their opinions over one founded on you being stuck even though the MMR dictates that you can't really get stuck in 40s solely to bad teammates.
I'm also getting this opinion from much higher ranks than you are probably (pro-players, solo/duo/trio queueing) pretty much agreeing that McCree and Genji can solo carry games while other heroes may not, or not to the same extent.