I love the art style, it is difficult and I admit I got stuck, but there seems to be a good variety of obstacles. I also did like the little drawing at the start where the controls were explained. Consider taking into account how long space is pressed to change how high the player jumps though (usually done by halving the vertical velocity of the player when they release the jump button) I actually found it a bit floaty.

A bit rough around the edges, but to me once you've submitted you've already done a lot of things well. This certainly isn't bad for what seems to be your first release on itch.io. I agree with other commenters saying that you could use a soundtrack and SFX but I would also look into adding small animations for different actions so the game feels more alive. If you're interested, making a game react to a player's inputs is a whole science. Here's a talk on the subject.

Since this is your first release I'll give you some miscellaneous advice (though you could totally know this all already):

Precision platformers like the one you made here typically have very precise controls to match, ones that are predictable and tightly controllable. I don't make platformers but sufficed to say one of the biggest things in making a platformer is tuning the movement to feel good. For more on this I recommend playing around with GMTK's platformer toolkit.

Similarly a lot goes into making a precision platformer "fair". As hard as some hard platformers may seem a lot goes into making sure their challenge is well telegraphed and isn't overwhelming for a player's skill level. Your game requires a rather precise movement for most obstacles. This would be okay if you could fairly and reliably see it coming. Maybe zooming out on the player to give them more vision could give them more time to react. Rhythm or timing are also potential forms of telegraphing you can use. 

Also, making the second obstacle move faster than the player means it requires an even more precise reaction time than just seeing it late would, and can lead to moments where the player has successfully reacted to the spike wall but still gets killed by it because they didn't react fast enough and get outpaced. Things like that (where doing reasonably well still gets you killed) usually aren't good in games because they signal to the player that the obstacle might not be surmountable at all. At one point I ran off the wrong side of the level platform because I was wondering if it was a trick like in I Wanna Be The Guy (an old rage game) and I was meant to go the other way from the start. Deliberately impossible hazards are useful for signaling to the player that they're doing something wrong or in the wrong place without having to explicitly say so (see the aforementioned I Wanna Be The Guy), but possible challenges should seem possible.

Still just releasing a game is an accomplishment, and I'm very proud that you released your first game! In 4 days! I had 2 months for my first successful game jam and it turned out so bad it's unlisted. Best of luck in your future projects! Consider experimenting with your current build and taking some of the advice people left in your comment section. I think you would end up with a pretty good game!

Nice game, I really like the simplicity of the art, reminds me of Portal lol. (BTW, if you have the time, it would be great if you could check out me and my dev team's game, thx :D)

Good effort with the loop theme.  

How do you do the second one?

Great time loop game, I like that you can only get through with trial and error. I wasnt sure how I was supposed to get past the third obstacle but thats cool. It would have been nice if the game had a soundtrack and some sfx as well.