Well, my dear friend, sadly, it didn't work. But, I found the solution - I baked all the textures into one and it is working perfectly.
I apologize for wasting your time, because it was clearly my game engine's fault and not you at all. Although, I sent you some donation as a token of gratitude. I'll be using this pack in my upcoming game and if it does well, I promise to donate more in the future.
Best to you and thanks for the help!
It's great that you were able to get it working. It looked good overall when I tested it, like in the picture, but I'm glad you found the solution. I tried looking at it from every angle, but I didn't think it was the textures. Don't worry, I always try to find a solution if something strange happens, but I'm glad you found it, my friend. Good luck with your next game, and thank you very much. I'll try to keep it to just one or two textures so that doesn't happen if you download another new character.