There were several reasons Jackson State didn't get as much attention. There was the obvious racial element. And the fact that it happened second.
But I think Kent State itself got extra (and lingering) attention from John Filo's striking photo of Mary Ann Vecchio's anguished cry. That helped propel it to international news, and a place in history books. https://www.loc.gov/exhibitions/images-from-americas-library/about-this-exhibition/icons/john-filo-kent-state/