When The Saints Go Marching In
This old gospel hymn is played in the New Orleans (or Dixieland) Jazz style that developed around the turn of the 20th century in (where else) New Orleans.  New Orleans Jazz is considered the earliest jazz style.  

In this style the trumpet usually carried the melody, the clarinet played countermelodies, and the trombone played rhythmic slides and sounded the root notes of chords or simple harmony.  Often a tuba or bass provided the bass line and percussion filled out the music.  Exuberance and volume were key.
