Where a few decades earlier orchestral composers and traditional brass bands and so on were the norm across Europe and the United States, jazz music seems such a stark change, and which arguably set the stage for rock and roll and so on.

Also given (to my understanding) the prevalence of white culture supremacy and xenophobia, it seems strange that the most popular music style first became popular with blacks and has roots in various cultures including African drums and Latin American music.

And yet I can watch this video of Belgians going wild for black Americans playing music inspired by Tunisia.

Am I perhaps overestimating the level of xenophobia during the time? And why wouldn't this music sound dissonant or uninteresting to people who were raised with an ear for traditional music theory?

Any further interesting information you could add or any sources would be appreciated.