Simplify the following text for a Grade 7 native English-speaking person.
Original: The group included Tim Staffell as singer and bassist , and , later , drummer Roger Taylor , who also went on to play for Queen .
Simplified: The members were Brian May ( guitar ) , Roger Taylor ( drums ) and Tim Staffell ( bass and vocals ) . When Tim Staffell left the band , Freddie Mercury replaced him and the band became Queen .