So after another 25 minutes of messing about, I finally was able to get the copy/pasted nolan from the demo scene working in a clean scene. For about 20 of those minutes, my character could move and pick up weapons but wouldn't shoot, so I had to re-copy the character multiple times before I learned the proper way to clear the bugs it was creating in the clean scene.
Just to summarize, I very much still firmly believe UFPS 2 would be greatly improved with a simpler method of creating a simple default character. To say that "a lot of people" are having to get creative and make their own prefab out of the demo scene's character kind of proves my point.
Right now, there are 2 ways to make a basic, default character: the intended method to go through 5-10 minutes of tutorial videos (accumulating to about 20 minutes of work to translate the tutorial into your project) or copy/paste the demo scene's nolan (but you still have to read documentation to learn that you have to find the Update Layers, Update Scene, Add UI, Add Buttons, etc. etc. and press them manually), and then hope you get zero bugs (I wasn't so lucky, the dang Player tag didn't translate between scenes but it wasn't the first bug in the list which sent me on a wild goose chase of bug fixes).
Maybe a button in the Character Manager for "Create default character" or something? Which then proceeds to update the scene and project with the necessary defaults as well a basic, working character. Or perhaps a system that uses Scriptable Objects to save a character, where you can save/load whole character setups, and then have a set of default characters included with UFPS 2 (First Person Simple, First Person Advanced, Third Person... etc.)
Just my 2 bits on the design of the software, as the way it stands now it's a real pain to get it going. With that said, I still like the code, thank you!