A polished and challenging platformer with good use of metroidvania elements. The music was also very fitting.
Here's some things I picked up on when playing:
There are quite a few leaps of faith in the platforming sections, most notably in the part with many moving platforms. Even though you did a good job of using coins to guide the player, I often died to the spikes as I couldn't see the platform below.
Some assets (most notably the coins) are scaled differently to the others and they have a different pixel size. Most of your assets look consistent though.
When I touched the box one too many times, the "It's too heavy" dialogue didn't fade back out again and I was stuck with it on screen. Perhaps if I waited long enough it would eventually fade out, but there is no need to see the dialogue once you are away from the box, so you could fade it out then.
The dash could do with some more visual effects. It was functional, but seeing the player jump suddenly across the screen didn't match the polish shown in other parts of the game.
Good luck if you continue to work on this game!