A musically inclined person who, instead of being a showman (like most guitarists, but not all) is more the
pure musician along with the
drummer, the pianist, and the mandolin player, the "musician in the group.
But the main
job (this, coming from a bass player) is to translate the languages between the guitarist and the
drummer, for they speak two totally different languages.
And popular to popular opinion, the bass player does not usually create the rhythm or even state it for the guitarist to play along with, it is the drummer that does that in most circumstances. The bass player in most occasions adds to that rhythm and makes it more complex, or creates a
bas(s)is for drum solos.