Actually, big band music was the impetus for the jazz movement that emerged in the 50's and 60's, including be-bop, cool jazz, west coast jazz, etc. A lot of the sidemen of the big bands went on to go into various forms of jazz because they wanted to break free of the strictures of the big band, which was really an ensemble. A lot of the great players came out of the Duke Ellington Band, Count Basie's and Woody Herman's big bands The big bands in effect became incubators for the great jazz explosion of the 50's and 60's which is what became symbolic of what constitutes jazz music. However, as noted above, jazz is a term that encompasses many forms of musical expression. I am an aficionado of many versions of this great American art form. I really like big band a lot. All of those horns really make the music kick.
I agree. There's nothing like a big band. I am in deep love with the Bill Holman band and the Charles Mingus Big Band.