As a Cajun, I agree. Cajun, Creole, Native American fusion that evolved over time to separate regional variations. The Native Americans were making a stew and using what is now called gumbo file (a thickener made with sassafras leaves and other stuff). The Cajuns use it mildly as such and started using roux more (now, it's sort of an extra source of flavor, the file), while the Creoles have a variation called gumbo z'herbes which is the main thickening ingredient. Creole, and some Cajun, variations were using okra as the main thickening ingredient but has evolved over time as well. Some still use okra but not as a stew thickener.
A long time ago, the Native Americans and Cajuns were using corn grits instead of rice. To Native Americans and Cajuns, the gumbo, for awhile, was a special occasion dish as well. For Creoles, it was a regular thing.