Can't lie.. Its similar tho. Arya had 6-7 seasons to build her arc as compared to Rey who only has 2 hours in movie format instead of a show's multiple episode format. Yeah Rey is the perfect and ultimate example of a "Mary Sue" but Arya was treading in "Mary Sue" waters cause there was no way she was supposed to body the NK and so easily as well. The NK was Jon Snow's arc and plotline since he joined the Knights Watch. Arya easily disposing of the NK was a very very strong case of "Mary Sue- Female empowerment that has overtaken Hollywood.
Jon Snow is more of Mary Sue then Arya Stark is.
Dude is pretty much perfect. Good looking (Melissandre wants to smash, Khalessi, Ygritte, etc), Great fighter, Great leader, a secret Targaryean so he has strongest claim to Iron Throne, can ride Dragons and most importantly is the
only character who continuously gets rewarded for not compromising his morals. Everyone else in the show get killed or punished for strictly adhering to their morals. Everyone but Jon Snow.
It would have been dope to see a 1 on 1 with the Night King and Jon Snow, it looked like it was leading up to it, as part of his arc. But in this case, 'subverting expectations' was done well imo. It would have been cooler if she was disguised as one of his generals and did it or even if Jamie Lannister did it. If Jon Snow did it, it basically confirms mary sue status.
Jon Snow is basically a shonen protagonist, he's infinitely more of a Mary Sue than Arya is.