You can really see that you have put a lot of energy and time into this game. I liked the artstyle and the general vibe, it was cosy. However, the game was not really for me.
I got frustrated early on due to the lateral jumping. I did not really understand the mechanic and instead jumped on the sign to get further. When I needed to jump on to the scaled box later on I didn't really understand how to progress and I fell down in the water. Paused the game to restart and found the bonfire option but that didn't work, nothing happened. Managed to swim under and get up on the other side. 
I reread the sign and managed to progress so not that big of a deal. And I guess I could have drowned myself to restart the game maybe if I couldn't get up?
I noticed that you gave information about what key to use for different controller. Nice! An improvement could be that you checked what type of controller the user had and changed the text based on that.
In the beginning of the game I basically only heard background music, there was no sound for jumping/swimimng/picking up crystals. I thought it was a bit odd because of the volume sliders suggesting that you had sfx and those type of sounds seemed like the most obvious to add. Messed around with the sliders a bit and noticed that there is probably something wrong with those. When all the sliders had the volume to 100% it worked as expected so I put them on 100 and then turned the volume down on my computer instead (I thought it was a bit too loud for me).
This is how the sliders looked like when I only heard the music. Maybe it was because I had the music higher than master? 
Overall a nice game! Looked good and seemed like there was a lot of content! I just did not feel it today so I did not play that much. I might come back to it another day :)