The podcast, The Roots of Jazz Dance, does an excellent job at explaining the why the roots of jazz are muddled. Lacking a standardized curriculum, Melanie George explains that jazz evolves alongside societal trends and cultural. Jazz dance history is thus a multifaceted realm of study, without linear developments. To explain, George describes particular jazz movements and how they connect to society at large. For example, she recalls the use of circles, which "honor the individual and the group," reflecting values in African culture. Just circles alone have a complex history!
Throughout the podcast, George calls on a variety of sources to support her claims. She cites jazz dancers themselves as primary sources (Billy Siegenfeld) and secondary historians with different specialties when drawing connections. For example, in a lecture by historian Veta Goler, the relationship between jazz dance/music is described using the stories of choreographer Dianne McIntyre. Given how richly complex jazz history is, sources to define the dance find it easiest to recall choreographers and dancers themselves, with some historical contextualization.