It isn't the norm
No, being gay or trans is not the most common. But being a native american isn't either, and in fact is even more rare (about 2% of the US). But you should be able to see why saying that "being native american isn't the norm" is a real asshole-ish thing to say and might get you into trouble with some people.
There are many variations in people. To label anything (that isn't harmful) as "not normal" is extremely dehumanizing.
How? I reiterate: every human being is in some way deviant from the norm. Whether you are homogeneous or heterogeneous in regard to a physical or mental characteristic, personal taste, ethical perspective, &c.
is associated with personhood, in the sense that it is part of what makes you the person you are. I'm struggling to see how "I am different from other people" equates to "I am not a person" in any sane worldview. A world where nobody deviated from any norm would be fucking horrifying.
I know it wasn't directed at me, but that's part of why I think all these linguistic games and identity politics are divisive bullshit. People are people, and if you need to distinguish some trait about them, use simple descriptors. It's immensely frustrating to live in a time where we really need to come together and pull to stop our species from sliding into the pit of extinction, but everyone seems to be caught up in all this petty hatred, devoting themselves to tearing others down and deifying themselves. We've had so many fucking centuries to reach the realization that our superficial differences are just that, but so many people still judge others and define themselves primarily based on those characteristics.
That premise is the real bullshit. I've tried it, and I've spent most of my life surrounded by people that think they live by it.
It hasn't stopped people from treating me like shit, even though I've tried for decades to assimilate. People still notice the shape of my eyes nose and body, the texture of my hair, the color of my skin, the inflection of my voice, my dialect, and the movement of my body. In case it wasn't obvious, "just being me" doesn't help either.
To make things worse, ignoring the identities of others makes it more difficult to empathize and communicate with them.
Without mutual acceptance of peoples' differences, there can be no means to peaceful coexistence. What you want is impossible.
You kinda missed the point. I'm not arguing that differences should be eroded, I'm arguing that they should be treated as what they are (unique identifying characteristics, personality traits, &c.) rather than automatic determinations of someone's worth or position in society.
Frankly, and I'm sorry if this comes off a bit harsh, but I don't really want to have anything to do with people who deliberately wallow in a shitty, pessimistic, fragmented worldview, telling anyone trying to move towards a less hateful future that they should just stop because it's impossible and not worth it anyways. Our history as a species has been, largely, one of overcoming and setting aside the fucked up things we do and think. I'm certain that at every step of the way there were people who said that things were just fine as they were, and others who insisted that improvement was impossible. Neither of those groups have ever been right, and neither ever will be.
I don't count myself as an optimist, incidentally. But I still think that our collective ability to stop doing stupid shit (even if only by waiting until everyone who doesn't dies of old age) trumps our ability to cling to it.