It doesn't seem to be visually coherent but it uses some models of mine so I gotta give it a try. I'll send some feedback your way once I got to playing it!
Wow! Do I understand your frustration.
GG is currently in no shape to make a 3d plattformer game. This game reminded me of all frustration I experienced in the 90s whenever I bought a lower middleware or cheap PS1 plattformer. To no fault of your own.
Your intro video and the humorous nature of the game certainly work for it and I think you have a decent game in you, but I don't think it will happen in GG right now. At least not this type of game.
I understand that 3d plattformers like this are a relic of days past and this probably doesn't draw too much of a crowd but I can only recommend any GG user to try this game because it shows a lot of actual effort in places.
I've been playing through 2 worlds and the way the camera rotates and the none precise way the character controls makes the plattforming a chore.
I also fell through the map several times and got stuck rather often. Considering how lowpoly everything is, it performs just as well as one of my cramped high poly levels which just should not be the case.
I understand that you might not be a 3d artist, thus I won't bother talking about a lot of unmodded purchased content as I can clearly see that you brought a lot of talent and passion as a game designer.
I fully relate to your wish to use a different engine after this attempt (which is real pioneer work in GG in this genre) and wish you the best luck with whatever engine you are going to use next. Please drop a link of your future work some day.