I need to simple files & folders browsing from my TV. Now there are lots of categories, for me are useless, I find very difficult with the remote control what I want.
How do I just show a simple folder to which I gave share, exactly as it is in the computer?
You can switch the libraries to display their content by „Folders“. That’s pretty much the closest to what you described.
Alternatively you could look into enabling the DLNA Server Part of your Plex Media Server and access the contents through that (which will give you a very generic interface without all the bells and whistles of Plex.