Interesting. But I'm not sure we actually got much of a character growth arc out of either Django or Schultz. Schultz didn't like slavery from jump, though he was not above using it to get what he wanted from Django. And Django wanted his wife back from jump and never wavered in that.
Perhaps Django's attitude toward other slaves changed, but I would argue that he was merely playing a role at Candyland until he and Schultz got exposed. So it wasn't like there was a sea change there either. More that he had to bury his real feelings until he accomplished his objective.
With Schultz, feeling some responsibility for Django, as well as disgust over slavery, it felt like a logical progression for him to take action against Candie like that. I don't think it was an epiphany kind of moment. Even his action, which imperiled Django and Broomhilda, didn't seem like a change in his character to me.
Agree with your take on Shultz. But with regard to Django, I don't think at the beginning of the story he had any use for any white man. Schultz broke through that barrior. I honestly thought that Django had something close to love for Schults in the end. So, I do think Django had some growth.
With Django's feelings towards white men. I ask, can you blame him? From what little we got of his past, white men had been nothing but cruel to him. So we do see some of Django's perplexed reactions almost from when he first meets Schultz that the dentist is something else all together than the white men that Django has dealt with. I wouldn't consider it breaking through a barrier, as if the onus was on Django and not the white men who had enslaved and brutalized him.
Also, Schultz wasn't above using Django's slave status for his own ends, despite his abolitionist leanings. So even there, there was some exploitation from another white man. But Schultz's other treatment of Django, as an equal and partner, did elicit an emotional response in return, or that's the way I saw it when he touched Schultz's corpse in the barn before grabbing Broomhilda's freedom papers.
Once again, I'm not sure how much that registered as a change in Django. His main objective was to get his wife back. Schultz was going to help him do that, so Schultz was useful to him. Schultz needed help in the bounty hunting business, so he needed Django. It was a mutually beneficial relationship, relatively speaking. But Schultz never changed from his abolitionist stance and Django never changed from wanting his wife back.
If there were any changes, there were not major ones, but of degree. Perhaps Schultz, pre-Django had been willing to live with the evils of slavery, but after meeting Django and Broomhilda, was more willing to confront it head on. His abolitionist feelings increased, but does that constitute a character arc?
Same with Django, he did have some feeling-of friendship, companionship-for Schultz. Even though white men had been cruel to him, I can't say it was beyond his capacity to not have some kind of fraternal feeling for any white man pre-Schultz. But meeting this white man that he could trust, that laid his life down on the line after buying Broomhilda's freedom (though his actions imperiled that freedom), certainly had an affect on him, but does that equate to a character arc?