Frogman, according to "Aficionados", Dexter Gordon puts this movies over the top by simply being himself, without acting; in addition to a fantastic jazz track that was sufficient for two records, plus the musicians were the greatest.
While a top actor, and a good script, could make a fantastic jazz movie for the movie going audience; Dexter Gordon signed, sealed, and delivered it for aficionados. That's because they saw a "real" jazz musician, with the idiosyncrasies of a working jazz musician. This is a jazz aficionados movie if there ever was one.
As you stated, "Too many considerations and different points of view as to what a "jazz movie" should be to give it such an exclusive ranking." My ranking was based totally on the music and the musicians who are so very outstanding; "Herby Hancock" is transcendental, and I use that word in the sense that he has been an accomplished performer in so many different genres of jazz, and his stamp is all over the place in that movie.
"Bobby McFerrin", is incredible, but I can understand your comparison to him and a horn; while I think he does the impossible, I'm not a horn player.
As far as considerations and points of view, if one simply compares jazz movies, and doesn't put so much emphasis on the music; "Paris Blues" was a better movie, and it dealt with the same subject "Expatriates".
"Miles Davis" is an "Enigma"; while I never met the man, some of the people in his autobiography are related to me, and they were his best friends. The Miles they knew, has no relation to the Miles the public has been presented. Just like his music, it's all about "which" Miles are you speaking of? That was an impossible movie to make.
Enjoy the music.

