A good start for an action platformer! The controls are quite responsive, movement is fast (but not too fast), the attack cooldown is nice and fast (but, again, not too fast). Lovely environments.
Here are a few suggestions:
1. If there was audio, it wasn't working for me. If you didn't implement any audio, consider that a little effort in this area goes a long way toward increasing immersion.
2. The player character kind of slowed down when falling next to a cliff. You may want to add a Zero Friction material to the Rigidbody.
3. There needs to be an indication of the player's health on the HUD.
4. I came across what looked like a boss, but it was totally inactive. If this is intentional (because the boss hasn't been activated yet), it would be appropriate to signal this clearly (e.g., by the character making an observation).
5. I picked up a couple of vials, but there was no indication of what they did. Powerups should clearly indicate their function.