Chaos
I think it would be a good idea to move all non essential third party assets to a subfolder like:
/Assets/Vendor/
Or if all packages are required, under:
/Assets/SimpleTPController/Vendor/
So you just need to copy a single folder/ it's more clear when using your package on another project :)
And i would also list the usage keys as there is no hint when joining the scene :)
And i don't know if it's the expected behaviour, but i see no icons when pressing TAB key:

Yeah, lol. Sadly this project is pretty much dead for the time being. Also yeah the icons were not yet integrated at this point in development.
Oh, what a shame, you sure spent big time making the kinematic implementation and inventory system. ¡Thank you for creating it and making it open source!