No, Jumbalaya is not yet a folk song. It has not gone through variations and been adapted to different cultures or changed in any way. A song by Irving Berlin is played somewhere in the world even today and his song pedegrees go back furthur than 30 years. But these are popular songs because they are attributable to one author, not changed and they are definitely not in the public domain. This doesn't mean, however, that in time they can't become folk songs. But they have to go through the process.

Frank Hamilton