0.9 Beta release! Feedback needed

Feedback needed:

Is the difficulty curve too steep? Are any levels too difficult? Or are the levels too easy for you?

Should I continue to make this a linear game (ie one path from start to finish), or should I add metroidvania elements? Or other types of non-linear gameplay, ie branching narrative?

Should I make the levels larger, or are they challenging enough? Currently levels are 4000 x 3000 pixels, but I can see making larger levels for especially hard challenges. Or vertical rather than horizontal levels, etc.

Is the minimalist look sufficient, or do I need better graphics? I think the days of me “hiring a pixel artist” are over, and I’d rather not let graphic resources be an impediment to my game design (I am primarily a musician and programmer - I’ve often had to rely on others to help with graphics.) Ideally I would stick with this graphic style, but lmk what you think.

Features I might add:

A timer - for speedrunning purposes. (You can use a timer outside of the game in the meantime.)

More levels - your feedback will determine how difficult I make new levels!

More secrets / unlockables - I’m currently only hiding one or two secrets per level. I can always add more secrets though. I could add more collectible items (like getting 8 red coins in 3d Mario). I could also add more hidden levels like Crash Bandicoot.

Notes from feedback I've already gotten:

It can be easy to get lost in this game. I plan to add collectibles as a way to help guide the player, similar to rings in Sonic. Unfortunately this idea didn't occur to me until late in development.

Certain people seem to be having visual glitches with the html5 version, because of course. If you see any glitches in the html5 version, be sure to report them to me.