Enjoyment 3.5/5 rounded up (4) - It is sometimes difficult to tell whether the platforming is frustrating on purpose. But when you pull it off you really feel like a ninja which I think is a big positive. It also helped I played this in a VC with a friend to laugh at my every mistake, which always increases the enjoyment of such things.
Execution 3.5/5 rounded down (3) - I think the commitment to minimalism on controls might have hurt this one for me a bit. Having TWO buttons instead of one would make it easier to play overall I think, and two is still pretty minimalist. Most rooms are fair or at least learnable; some of them feel like nonsense in a bad way, including the final boss TBH.
Sensory 3.5/5 rounded up (4): Cute but basic, committed to its bit. The music fits, and didn't grate on me too much, but some changes in that regard might have been welcome at some point.
Metroidvania 5/5: Within its constraints it is a proper and fairly well-designed map overall. Not sure if I missed anything as to secrets.
Theme-relevance 5/5: You did a LOT with a little. The controls occasionally felt like an enemy in themselves but when they weren't doing that they were solid.
Overall, feels like a good game in the vein of a UFO-50 sort of "old school but what if" sort of project. You could (maybe, hard to know with pixel art platformers) polish/expand this one and sell it.