N.O. was unique in many ways, perhaps the most significant for this discussion was that it had the LARGEST community of FREE Blacks in the United States.Largest concentration of non-White (Black) wealth in the entire country in the 19th century.
In fact, I'm amazed at the details of the true wealth and land holdings that N.O. Creoles had, and how well educated their children tended to be because of that wealth. Including private instruction or being sent to Europe to study. Some of the Creoles who became musicians were taught how to read and write music across Europe or from the French and Spanish institutions in New Orleans.
Not surprising that a person from that social group, Jelly Roll Morton's mark in music history is being the first one to put jazz music in published form/composition . Having access to ALL of the musical influences that came into New Orleans..as well as the formal musical instruction .
I have pages of Jelly Roll's biography where he talks about the privileges that being part of the N.O. Creole community granted access to him , even not being from one of the more prominent families.
He details his family attending the local French opera house concerts, how he took private music lessons (from a Spaniard) at 6 years old , taking music lessons at St Joseph's University as a young man, and other private lessons from accomplished musicians/instructors as a young man. That wouldn't have been rare for a child born in that social circle, Morton was just an exceptional talent.
actual pages and link in the spoiler
So for the last time, when Morton writes of the Spanish tinge that HE believes is essential to playing jazz, it is not mis-speaking, it is not "he didn't know "....it's a man who has had access to all kinds of influences, training, performances, and music detailing DIRECTLY what he's talking about.