Amazing Idea! This is a really interesting take which could be turned into a fully fledged game.
The gameplay itself feels unfair however. Sometimes there is no way to avoid the arrows, and you're forced to die to them. Other times you die to a spike and have to walk all the way to the thing you need to avoid to die to it. It gets tedious after a while. More variety in what you can die to to beat the level would be a great addition and make the game much more fun, as well as making death more fair, with arrows being more avoidable. Giving the enemies visual and audio queues when they fire would definitely also help.
The art style is great; both the cover art and pixel art are really well done! It feels unique and gives the game character. However, sometimes it was difficult to tell if you were immune to a certain enemy, due to the colour scheme being similar.
The music gets very repetitive very quickly, since its only a 15 second clip looped. I would make the song at least a minute and a half long, so it doesn't become a nuisance and stays engaging. Adding sound effects would also be a bonus. Especially when you reach a checkpoint, die or an enemy attacks.
There was no clear explanation as to how the game mechanics worked, so I had to figure it out on my own. Explaining core mechanics is essential to engaging a player, so they know how to play your game to begin with.
This has a lot of potential! It just needs more polish and playtesting, and it can be a very solid release!!!