As as first game it's not too bad at all. That said, there are tons of ways you can improve it!
- The movement doesn't feel very good. There must be a technical problem, because the movement in my game looks totally different than what's in your gameplay video. While on a planet mine moves at a third of the speed, making most of the jumps impossible. You might need to move your physics code inside FixedUpdate, or scale it by delta time so that it feels consistent across all platforms. - Jumping and hitting the bottom of ledges didn't feel great, and you might want to make those one-way colliders instead. The visuals give a bit of indication that you should be able to jump through and land on top of them. - When changing directions, the character's collider moves around which leads to unintended consequences. I can be standing on the edge of a ledge just fine, but as soon as I change direction I fall down off of it. When you flip the character between left and right, make sure to keep the collider and art centered so stuff like that won't happen.
You're off to a good start though! Keep tweaking it and improving!