kids can have opinions and thats fine, some of them precocious. but generally theyre opinions are still very nascent, theyre still in their formative years of thought, beliefs, understandings, experiences. why is it that only adults have an issue with this? because its a broad meaty topic and adults can analyze and incorporate other aspects of life as analogies.
anyway, the issue is not the diversity per se. its the re-booting of movies/etc with agendas of identity politics and sexual preferences and other SJW elements, and the meta or fourth wall of their scripts....instead of focusing on writing solid stories, or, creating new IPs to fill with diverse characters and then theres no problem.
also, the general thing now thats going way out of control of people getting offended bu everything. theres no fun left. look at the recent DSA conventions for where all this is going.
You still haven't said why it's a bad thing. Re-booting is lazy for sure - I thought the new Ghostbusters was a bad idea. Not because women were the lead characters but because the original was a classic and any reboot (with male or female leads) was going to flop. Using the DSA (a fringe group) as an example of why showing diversity in movies is a bad thing (in your opinion) is just plain silly. Extreme political correctness is silly - having a female Thor is not extreme political correctness.
Don't watch the new Thor, if it's such an issue for you.