How did jazz grow partly from blues and ragtime?

Jazz emerged in the early 20th century as a distinct musical style by synthesizing a variety of vernacular elements, with blues and ragtime serving as foundational components of its composite matrix.123

The transition from these forms to jazz occurred as musicians began to adapt and expand upon existing styles:

• Embellishment and Improvisation: Many musicians, particularly those unable to read music, learned ragtime and popular dance tunes by ear. Out of necessity, they began to embellish these syncopated melodies, a process that naturally evolved into improvisation as they "loosened up" the rigid structures of ragtime.2
• Structural Integration: While ragtime was typically a fully notated, through-composed piano music, jazz musicians began to incorporate the 12-bar blues form and 32-bar song structures, moving away from the strict march-derived sections of ragtime.2
• Synthesis: Early jazz pioneers, such as Jelly Roll Morton, assimilated these influences into a new, coherent style. By the late 1910s, the line between playing embellished rags and improvisatory jazz had become increasingly tenuous for many performers.2

Ultimately, jazz transformed these influences into a primarily instrumental, communal music defined by complex syncopation and individual expression.23