Simplify the following text for a Grade 6 native English-speaking person.
Original: These are the founding members of Jamiroquai and were involved in the writing and production of the first album . The lineup of the band has changed several times , and the longest serving and now core members of the band are lead singer and songwriter Jason `` Jay '' Kay and drummer Derrick McKenzie ( 1994 ) .
Simplified: The members of Jamiroquai have changed for many times , except Jason Kay .