Bass is the instrument people take up expecting to be in the background, and then discover they are holding everything together.
Your job is to agree with the drummer, precisely. Not approximately. The gap between a band that sounds tight and one that does not is usually measured in fractions of a beat between the kick drum and the bass.
Professional players spend most of a set playing root notes. Playing the simple thing at exactly the right moment is the job. Everything else is decoration.
A guitarist needs months before anyone wants them in a rehearsal. A bass player who can hold a steady root note through a song is useful within weeks, and being in a room with other musicians accelerates everything.
