Aspirational Heroes are Wish-fulfillment Fantasies
Young readers (and writers) are attracted to aspirational characters. They kick butt in tights, and take no sass from tyrants. They conquer corrupt governments with a crossbow. They are the slave who becomes Pharaoh, the outsider who becomes Savior, the underdog who wins.
Arguably the biggest appeal of these characters, beyond identifying aesthetics, is that they are invulnerable. This is sadly not how real life works, but that's not the point. These characters endure because we all relate to being underdogs, and we all want to win. The more vulnerable at the start (baby in a wicker basket floating down the Nile); the more powerful by the end (P̶h̶a̶r̶a̶o̶h̶ ̶o̶f̶ ̶a̶l̶l̶ ̶E̶g̶y̶p̶t̶ BFFs with God and magic superpowers that defy nature).
Mary Sues are also Wish-Fulfillment Fantasies
Heroes are such wish-fulfillment fantasies they are almost a Mary Sue, "the youngest Lieutenant in the fleet — only fifteen and a half years old" – except one important difference – Mary Sue is never an underdog. A Trekkie's Tale is 5 paragraphs of fanfic satire where the original Lt. Mary Sue basks in unearned glory and adoration.
This is the difference between the Hero's Journey and the Mary Sue. The Hero-protagonist starts with nothing and works his way up – if he was born wealthy and privileged he must lose it all first. He faces challenges and suffers. He proves himself through bravery and cunning. He earns his status through a series of trials, and by the end he is a scarred but wiser warrior. Alternately he becomes the beautiful princess but only after scrubbing floors and being abused by wicked stepsisters.
In contrast, Mary Sue commands the ship on her first day, she wins a Nobel Peace Prize, and is half-Vulcan because of course she is. There are no consequences to her being half-Vulcan, no one called her names. She never experience bigotry at Star Fleet or was denied employment and housing for being physically different because she lives in an idealized fantasy that is designed to flatter her.
Mary Sue is Cosplay
A protagonist who appropriates the aesthetics of an underdog, but does not experience any reduction in status or consequences, is like fans who cosplay at a convention center. They are not superheroes, they are just dressing like them. It's a costume, a costume without consequences. They take off the costume and go home.
As writers, we have an obligation to view our protagonists' tale as a heroic journey complete with hardships and failures and the odds stacked against them, and not as flattering and universally adored version of ourselves – if only we had the guts to dress in a superhero costume everyday.
You are the author. You get to say what the rules are, and you can write whatever you like. If you want to change the entire universe to "normalize" your character, that's fine it's your choice. But why dress in a superhero costume in a world where superheroes aren't special? There's actually a trope for this "Bizarro Universe" where everyone acts like Superman. Bizarro showing up in our universe is an interesting contrast (to Superman), but Bizarro living in Bizarro World isn't interesting for long. He isn't special, he's exactly like everyone else.
Assigning cherrypicked physical traits of real-life disenfranchised people, and then putting them in a world that functions exactly like White Cisgendered Patriarchy doesn't win any points for diversity. Ursula K LeGuin loved to puff herself up because the characters in Earthsea look like Native Americans, but she set the stories in pseudo-mythical Europe with wizards and dragons so nope, sorry, no diversity points for Ursula just for casually mentioning they are brown. See also: J.K. Rowling's Nagini controversy for naive diversity backfiring on the author.
Just saying the character looks a certain way in an offhand descriptive infodump, without allowing it to have any meaning at all, is a political act: erasure.
Aspiration or Mary Sue?
The younger the reader, the more we need aspirational characters to spur our imaginations – "If you can see it, you can be it." But naive representation and appropriation without consequences are shallow and problematic. You can't "aspire" to live in an alternate universe, that's not a message that elevates anybody because it will never be real.
As much as we want to boost our talent as writers, we cannot write myths. We must write stories. We don't have the benefit of eons to elevate our wish-fulfillment fantasies to the level of epic poetry. Our stories exist in the real world, and when they deny that the real world exists they are not called "aspirational" they are called "escapist".
Escapism isn't inherently a bad thing, but the older we get the less "honest" this sort of false-representation feels. People who are actually disenfranchised in the real world are unlikely to identify (they are more likely to be offended by being erased), but readers who are exploring gender-fluidity in their youth (which is essentially everybody) may get a kick out of seeing an alternative-looking cast of characters, even if that diversity is only skin deep.
I ask you (rhetorically) what do you want to say with this character? Alternately, what do you want to say about a universe you need to change to put your MC in a safe-space where their existence is unchallenged? Knowing something of your other questions, why would the MC rebel against a world that flatters them? What are they fighting for?