The content that bothers part of the American public is as ridiculous as the stuff the American public laughs at Disney for censoring because of China.
For some Americans, the only appropriate protagonist is straight, white and male. There have been some huge exceptions, but that's because there's actually a pretty big market for it and those stories were good enough to blast through those expectations. Does that reinforce the idea that story is the most important thing? Sure, but let's not pretend that the bar isn't MUCH higher for diverse characters. And gay characters? They make up a big chunk of the population and yet are mostly banned in Disney, any characters who lean gay always generate a ton of outrage.
I mean, a lot of this is true but there's a TON that goes into these things and you're getting into some really deep stuff in terms of the human psyche. People tend to be tribal, and tend to gravitate toward things they can most closely relate to. And the exceptions are generally that if they can't closely relate, they at least ASPIRE to it.
You can probably toss out the "male" part at this point though. Female protagonists can and do smash at the box office and narrowing it down to Disney stuff that's geared towards kids (since that's the thread topic), females have taken the lead more often than not. Frozen is the biggest financial success the company has ever had and the two leads were female. And it's not like that's a one-off, Disney has a LONG history of successful movies with female leads (Snow White, Sleeping Beauty, Princess and the Frog, Tangled, the Scottish one with Meredith--can't remember the name LOL, Moana, etc etc etc). MOST of their kids movies feature female leads. I know, my daughter watched every one of them numerous times when she was younger.
The reality is that movie studios are for profit and eventually if shareholders aren't getting the returns they want, smart execs have to ignore that maybe some white people in a perfect world would be more open to minority or gay lead characters. Honestly, even the minority angle is fading IF they make a movie where a minority lead is compelling and makes sense. Moana did extremely well with a female minority lead, because...duh, everything about the character fit and they made a movie that captured kids into the story.
For a lot of Americans in terms of the gay aspect, it's just comes down to how well they relate. As I said before, Americans want either characters they relate to or characters they aspire to be. For 90%+ of the population, an outwardly gay character (assuming that's made clear and is some part of the story) doesn't fit the first part. It CAN fit the second depending on other factors but since the overwhelming majority of those taking their kids to see movies are straight (not that there aren't gay parents, but they are obviously a tiny minority), they gravitate toward characters that match to some degree their own lives. It might not even be a conscious thing.
The thing is, there's a reality for the future that is going to make conversations like these largely moot. Not in our lifetimes, but it's coming. Down the road, most Americans will be some sort of interracial mix. The world has shrank, the stigmas of interracial procreation are disappearing, and this is going to be a nation of mainly light brown skinned people. The gay aspect will become less of an obstacle as well, people care less and less about it as time goes by. 20 years ago a gay couple as protagonists would have seemed at the very least a little bizarre to me. Now? Barely a thought. I watched that M Night Shyamalan movie with the gay dads as the two protagonists and I didn't really even think about it until a scene where one brought it up as a reason that the crazy thing was being done to them. So I guess if this is something that bothers you, I'd say at least feel good that after we're gone sometime in the future these issues largely won't exist.