Complex sentence: Pianistic improvisation in the jazz idiom by such luminaries as Art Tatum, Phineas Newborn Jr., Sun Ra, Cecil Taylor, Keith Jarrett fascinated James more than anything and would prove to be a major motivator in his dedication to the instrument.
Split into simpler sentences: Pianistic improvisation in the jazz idiom by such luminaries as Art Tatum, Phineas Newborn Jr., Sun Ra, Cecil Taylor, and Keith Jarrett, fascinated James more than anything. They would prove to be a major motivator in his dedication to the instrument.