My first opinion was that you don't know what a metroidvania is because of the simplicity of this game...and then I went to the left and immediately discovered a locked gate, along with a view of a reward for passing said gate (an incentive to explore and find the ability that will allow you to do so). It's clear that you understand the principles of a metroidvania, even though (if I had to guess) this is one of your first times making a game. Bonus points for making a surprisingly-enjoyable game!