Music is art. Music (created or copied) comes from inside the musician and is delivered via the instrument of choice.
Playing (music on) an instrument requires the brain to combine the mental with the physical: the musical skills and the manual/technical (gymnastic) skills.
Learning to play music is a twofold process, one is assembling the music-related parts (like intervals and rhythm and such) and the other is perfecting the manual elements (like playing rolls, fretting and such).
Of course, learning to play an instrument makes no sense unless you grow a repertoire of set pieces that you can perform, which in turn comes from your knowledge of the bluegrass genre.
The whole bluegrass music thing is pretty complicated and tangled--you need a simplified roadmap (one that views the banjo learning process in the wider context of performing bluegrass, and that in the yet wider view of MUSIC in general.