This is amazing grate job on your first game. i love your art style for this game, sadly i don't know French (i would like to some day) but otherwise this is a really a nice little game. Two little things i found was at one point in the game on the way to the cat there is a rock that gets blocked by the parallax from the tree when walking by it so for better visibility you might want to get rid of the tree or maybe move it, and also some time the dog would get stuck on slopes, but overall i had no problems. 
p.s. i'm also a more visual person when it comes to making games, a good game engine you might want to try is Godot it is really easy to use and grate for 2D games.
Good luck on your game dev journey :)