Simplify the following text for a Grade 10 native English-speaking person.
Original: Widely considered one of the most influential musicians of the 20th century , Miles Davis was , with his musical groups , at the forefront of several major developments in jazz music , including bebop , cool jazz , hard bop , modal jazz , and jazz fusion .
Simplified: He was very important to 20th century music and helped to develop several different styles of jazz , like cool jazz , hard bop , free jazz , and fusion .