So in the demo, Jerbo just shows up in your party. Initially that wasn't the case, but the fights were way too simple and boring (because you know... the beginning of rpgs are like that) so I basically set the party to early-mid game instead of beginning of the game, and made the fights there a bit more difficult to show off the fights, which doesn't really happen in this part of the game (which again... the beginning of rpgs are like that). In the full version of the game, only Jeebo is present during this entire section of the game, and you unlock Jerbo upon entering the city with a full introduction and everything.
As far as the list of controls, are you talking about the Obligatory Tutorial that says Z - Interact, X cancel, Backspace - respawn, Escape - Pause?
The rest of the "tutorials" are on those signs, but I was afraid that if I didn't tell players at least the very basics they would likely not know how to interact with things or anything like that.