You did a fantastic job capturing the era. The aesthetics and audio were absolutely on point, and it genuinely felt like something that would have come out of the old NES library.
The controls did mess me up a bit, but that's probably just a me thing as I constantly had to tell myself to move using my right hand and act with my left, not many games I play control like that so it took some getting used to.
Only gripe I have can actually be seen as a compliment really. This game's difficulty is also very authentic, in that it is incredibly hard and feels like it punishes you for things you couldn't have known outside of trial an error. It's very fitting for what you were trying to replicate but dang it doesn't mean it isn't still frustrating. Just when I'm starting to get the hang of it I get blindsided and run out of lives and have to do everything all over again. It's a perfect match for the kind of brutal, old school difficulty reminiscent of quarter eating arcade games that the era used to have.
I personally dislike games like this as they tend to fuel my anger and I don't get that same rush from overcoming it that others seem to. THIS IS VERY SUBJECTIVE. There are plenty of more hardcore people who I know who would love this exact kind of challenge and gameplay, it's just not for me.
A great entry that you should be very proud of! I really wish I was better at it!