This GDD was a pleasant read through and a mini-adventure in my head as I read it.
Harkening back to things like Sonic Unleashed and referencing A Hat In Time helped me paint a mental picture of how the level design might happen and seeing the personalities of the characters in their actions throughout the game.
You have a great deal of developed ideas here and that will help people understand exactly what they're getting into with this game project. With a little visual reference and maybe a sample "slideshow" of level progression it could come together as an awesome anchor for the project!
As others may have mentioned, this genre isn't necessarily something new, but regardless of that you have something great cooking here! I look forward to seeing where your work and the project go!