Was browsing games in Minetest's catalog and found one with some... familiar graphics. Yup, I made them! Well, some of them. XP
I found it rather odd the way muffins are used. Instead of healing, they add stat buffs that wear off after a few seconds. It caught me off guard at first, since there's no timer to tell you how long you have left, and it seems you have to die to make them respawn. But then I don't think this game intends to be a one-to-one remake of Mario or SuperTux in 3D; it's cleary its own thing. Though, if you'd like, I could make some custom item icons that would be less confusing. Get in touch with me and let me know what you need!
Gameplay-wise, the levels are good, but seem a bit advanced. I think you should make some short and simple ones first to get people accustomed to how stuff works. It'll also help prevent burnout when designing levels if you don't start out with all your advanced ideas first. If possible, find a way to make moving platforms move the player, too.
Not sure if this is doable, but one feature request would be if the third person camera could have the player avatar turning independant of the camera's angle. Think like how the 3D Marios or Breath of the Wild do. If it's not doable, don't sweat it, but platforming is way easier in third person.
Overall, though, this is an amazing start, and I can't wait to see where it goes! And again, feel free to get in touch with me for any graphical requests you have.