"It sounds like the words 'blues' and 'jazz' were first used by people who didn't initially create the music they referred to by those terms, and the meanings were not initially clear and unanimous among the people who used the terms."

"Jass" or "jazz" was a name that caught on in Chicago to describe peppy music such as ragtime with collective improvisation by visiting bands from New Orleans.

What make you think there was relatively little consensus about what "blues music" meant as of about 1909-1911?