Thank you for your review ! I made a level editor because my friend (who was working with me on the project) didn't know anything about unity, so I spent the first day making this editor lol. Because of this, I didn't have enough time to polish and balance the game, so only the first level is very hard :/
There is a walkthrough video if you are really stuck : https://youtu.be/sEtgHb3ZkU4