Not bad, actually did like the use of the main mechanic when you had to make the switch between carrying the chest and carrying whatever other asset you'd need to actually move forward in the level.
The chest/barrel throwing did get inconsistent at times, specifically on level 3 where the throwing distance/speed seemed to changed depending on how far away the next platform was. There was not much need for that as just keeping it at a constant speed would've made it more easier for the player to know how to work their way through the level (like how enemy AI in espionage games have very predictable behavior so players would know where and where not to go).
Also I actually succumbed to the same fate as Naishi (i didn't know he also played the game) because I got a little too curious and got softlocked out of level 5 and couldn't complete the game afterwards. Players will get naturally get curious so playtesting with a mindset of a kid that wants to break everything they come across helps a lot in identifying what can stay that the player can explore and what should be closed up.
Last thing with the character sprite, being more blurry than the rest of the assets. Since it's in Unity (I've experienced the same problem in Godot) there should be a setting that allows you to change how the textures are filtered. I don't know if it was applied for everything except the character sprite or something because it was kind of jarring to look at him while seeing everything else with crispy 16x16 pixels.
Nonetheless, congrats on your game!