Famous jazz musicians of the 1950s had varying opinions about the emergence of rock and roll. While some musicians embraced it as a new form of music, others were critical of its simplistic and repetitive nature.
One famous jazz musician who spoke positively about rock and roll was Duke Ellington. In a 1956 interview with Downbeat magazine, Ellington stated that he saw rock and roll as a "new form of expression for the young generation." He also praised the energy and enthusiasm of rock and roll performers, saying that they "give everything they've got."
Another jazz musician who appreciated rock and roll was Louis Armstrong. In his autobiography, Armstrong wrote that he enjoyed listening to rock and roll records and even covered some rock and roll songs himself, including "Blueberry Hill" and "Hello, Dolly!" Armstrong believed that rock and roll was a natural progression from jazz and that it reflected the changing tastes and attitudes of younger audiences.
However, not all jazz musicians were as enthusiastic about rock and roll. In a 1957 interview with the Chicago Defender, saxophonist Sonny Stitt criticized rock and roll for its "monotonous beat" and lack of improvisation. Similarly, pianist Thelonious Monk dismissed rock and roll as "not music" and claimed that it lacked the complexity and sophistication of jazz.
Overall, the opinions of famous jazz musicians regarding rock and roll in the 1950s were mixed. Some saw it as a vibrant new form of music that reflected the changing cultural landscape of the time, while others dismissed it as simplistic and lacking in musical depth. It is important to note that these opinions were not necessarily representative of all jazz musicians or music critics of the era, as there were likely many different perspectives and opinions regarding rock and roll's emergence. The sources cited in this answer provide insights into the thoughts and attitudes of some of the most well-known jazz musicians of the time.