Hello!
This very much seems like a learning project so congratulations on getting something together to this point!
Firstly I would recommend zooming the camera out as the game felt very closed in. It also seems like you were using prefabs with colliders built in for the environment blocking which I think lead to some issues with walls that the player could phase through. Maybe look at blocking out the level and box colliders as separate layers so there are less seams between the colliders to reduce the potential for clipping? I think the general platforming felt okay but definitely could use improvement. The jumping felt very floaty which could be addressed by changing the way force/gravity is applied to the player when they are rising/falling. Often these values need to be different for the jump to feel nice for the player. I would recommend setting yourself up a test environment with a platformer player controller with some of these aspects exposed in the editor so you can play around with the values until you find something that feels good. On top of this some another trick to look into is coyote-time which lets you jump after having just left contact with a platform can also improve game feel. There are just so many ticks you can use to help a platformer character controller feel good I'd recommend trying out a bunch of them to see what you like. Good job putting this together though, it's still a tonne of work getting anything playable so keep at it!
Our team have submitted a square-guy platformer too that combines Tetris and runner elements if you'd like to check it out (Link below). :)
I wish you the best with your projects!
https://itch.io/jam/feedback-quest-8-indiegames-x-indie-streamers/rate/3773442