It's called spin. Take credit for someone else's IP, connect it to something controversial to make sure there is discussion about it generating desire to see it, outright distortion of the truth to promote something, your guess is as good as mine. You don't really think that they wouldn't connect it with the movie to make it their own do you?
On top of that, the "Stories" happened so long ago that to say that it was based solely on the literature would be like talking to most of today's public whose eyes would glaze over and they would go blank. Disney would have said that was what it was based on because that was the only recognizable way to put it. I already said that if you want to believe it was based on SotS, there is nothing I can say to make you understand it, so whatever floats your boat is OK, but, if you can find one thing in that ride, as far as show goes, that isn't directly connected with Uncle Remus, I will be happy to agree. The movie Song of the South was connected and inspired by Uncle Remus and the then existing stories of Brer' Rabbit, etc. So in a very indirect manner, the idea is inspired by the movie because they owned that property, however, since the movie was inspired by the Stories... which one is the lead idea in both of them? But, still no direct representation of any of the SotS story line, just the Uncle Remus ones. In the meantime, continue to believe every bit of information that is spun by the Disney PR machine. They depict things exactly as they are all the time.