Personally having a bunch of nonwhite, LGBT, mentally ill/neurodivergent, etc characters just felt right.
For one thing, I care deeply about people in general, and I know how big a difference representation can make. While I'm never going to be the person who gets us to Mars, I can still change the world for someone out there with my art.
For another, I fall in love with names. Sometimes I create a character knowing only their name and extrapolate from there. So, since I love many names from different cultures, sometimes I'll decide a character's ethnicity or nationality based off their name.
And finally... it's more accurate to my life experience. Like, I live in a kind of rinky dink southern Arizona town. We don't have a lot going on. Our population is around 40,000. Our claim to fame is that we have the first McDonald's drive thru, and we're kind of nearby the historic site of this famous shout out. But yet, in my two years working at McDonald's, I meant so many different kinds of people.
Most of my friends are queer, mentally ill, disabled, etc too. Plus, y'know, there's me.
Admittedly, this current story does explore things like gendered expectations/socialization and trauma. But that's the kind of story I want to tell, because it's interesting and those experiences have made my life what it is. A lot of people champion representation where a character's marginalized status is only a small thing in their life, and that's cool sometimes, because it is like that for some people. But for a lot of us our sexuality/gender/disability/race/etc are a big part of our lives. They affect how we're treated, how we think of ourselves, how we learn to interact with others - so many facets of our lives. My entire personality isn't "trans bisexual with ADD/autism/mental illness/several other conditions", but you're nuts if you think it hasn't in part made me who I am today.