*The following analysis is my opinionated viewpoint, not fact.*
One thing i've always admired about the very early Disney classics (apart from the impressive animation and inspiring storytelling) is that they've always been big on Animal Rights. You may notice that a few of their films, mainly the ones that feature animal characters, base the film around a certain animal commodity that they feel they need to spread awareness about. And they do so by reaching out to kids. Dumbo was the first, but not the last Disney film to do this. I won't list the other films just yet (but some of you may be able to guess some of them, there are currently seven that i know of).
Released in 1941, Dumbo was Disney's 4th animated feature. I trust that most of you know this story, so i won't bother explaining the plot. The very basic moral of this story is obviously 'believe in yourself' and that what you think is a huge flaw may in fact be a gift etc. But this film also explores the plight of circus elephants. And personally, i believe they portrayed the issue very well. Particularly when Dumbo's mother is chained in solitary confinement, after being condemned as dangerous because of an angry rampage after people made fun of her baby's big ears. The scene that followed became one of Disney's saddest moments in their history. The scene known as 'Baby Mine' where Dumbo is cradled by his captive mother through the bars of her prison, with tears running down his face (and the face of everyone else who watches this scene).
On a side note, i always wondered why Dumbo and his mother were the only characters that couldn't speak (except for Mrs. Jumbo's one line at the beginning). But i think i may have figured that out. This is just my opinion, but i think it's because they were trying to convey the message that animals suffer in silence, so Disney decided to mute the two characters that suffer the most in this film. I don't know, it's a thought. Let me know what you think about it.
The life of an animal trained for the circus is already harsh, so imagine that same animal having its own mother caged as mad due to a stupid misunderstanding on the part of the human being. Perhaps the fact that Dumbo and his mother didn't have the gift of the speech (unlike Timothy, the crows and the other elephants) is just as you mentioned, to emphasize the pain and suffering and not be able to defend themselves.
Marine parks with performing whales are also cruel places. It is like a circus, but with whales. I have learned a lot about that as well. There is a grim disturbing documentary about captive orcas. It focuses on Tillicum. It is called Black Fish. That taught me a lot. Afterward I watched Free Willy. Then I understood the story and the conflict much better than when I was a kid. Free Willy can be a spokesperson for animal rights as well.
One controversy is deer hunting. It is a a complex issue. Personally I believe that hunting is wrong, unless it is done for food. The Bambi movie is notorious for traumatizing kids. Even you have some pictures with Bambi in it. So he can also make a good spokesperson. Deer hunting is a major problem in the movie. However it doesn't convey the complexity of the issue in real life. I don't know what is the motive of the villain, man. It would affect my judgement on whether he is good or bad. It depends on whether he is after venison or after a trophy. If I could pick, I would rather go with the venison hunter. I like having redeemable villains. I accept that someone kills deer for their meat. That is just how the natural food chain works. I care about animals, but not enough to go vegetarian. Although if one really wanted to go that far, another spokesperson is Wilbur, the pig from Charlottes Web.
I just thought I could throw some ideas out for you.
Dumbo can't speak, yes, but ... he's a baby. I think they thought the plot was cuter and most innocent portraying him this way. But hey, those are just my thoughts!