Okay! Definitely not a bad start, but you said you were looking for feedback, so, here it is.
The physics, for the most part, feel pretty okay! The game wasn't buggy at all, and the controls were responsive. My only complaint is that the player's jump arc doesn't feel super balanced-- imagine tracing a path behind the player as they jump, and you'll see it goes SUPER high super fast, and then they land before making much horizontal distance at all. I think the game would feel better with a slower jump (and weaker gravity to compensate), along with a faster walking speed, so you could cover more horizontal distance. Right now, up is easy, but side to side feels a little slow.
In terms of the level design, there was nothing wrong with it, but it all felt a little bit same-y. One thing I like to do when I make games is make sure each level has something 'special' about it! A reason to remember that one out from the crowd. For example, maybe one level has special enemies which slide around at you really fast, and in order to defeat them you have to get them to slam into a wall. It doesn't have to be new enemies or mechanics though, it can be the same mechanics 'structured' in a different way. For example, with what you already have right now, you could make a level that is a series of rooms filled with enemies, and in each room you have to get a key to move on to the next one. That's just using the things you have in the game right now, and already, that level would feel super different to the ones you have in right now! I like that the theming changes around (i.e. grassy area vs desert), but it can help keep players interested when the gameplay is varied as well.
There are also a few other things you could change around-- For example, jumping on enemies is missing a little bit extra *oomph*. Maybe you could make a sound effect for it, and make it so you bounce up when you land on them, instead of just falling to the ground. Maybe even a particle effect for killing enemies (or collecting coins!) Speaking of sound effects, the sound for collecting the apple is just a little bit too loud.
Don't get me wrong, by the way-- I've been focusing on things to fix since the description said you want feedback for the final version, these are just some things to consider. There are plenty of parts of this which are solid-- the controls feel responsive, collisions (with platforms and with enemies) feel fair, and Pacby is pretty cute. Oh, and the gameboy filter is a really nice touch. You just gotta give it that little extra spice that sets it apart from the crowd. (and music would be nice too)