When I was a young musician and writer I didnt think about an audience and I did whatever entertained me, first. I never was a people pleaser, a yes man or a pushover, that type of person that says, "What do you want me to make?! What do you think I should play?!" I did watever I wanted to do the way I wanted to do it. I didn't have a target audience. I thought man if enough people like my stuff as much as I do I can make some money at this.
When I became smarter and more talented and practiced and knowledgeable I started to realize that I needed to get into genre writing if I wanted to develop my craft or be stuck in freelance yes man hell. So I stuck to subject matter related to what I read and what movies I watch and my personal interests.
I suppose my target audience would have been people much like myself that I could relate to in life. I never was one of those writers with an agenda pretending to be something they're not in order to secretly target a specialized audience to influence them in some way. I like science fiction and used to like horror, I like action and war and all that so thats what I stick to.
Unlike many authors I don't try to appeal to other age groups or ethnic groups either. I stay in my comfort zone when writing. I might occasionally use a child or an elderly person in my stories but my target audience is my own age group and lifestyle group.
I can't imagine being that middle aged man writing childrens stories, you know how weird that sounds? Best leave the childrens stories to women, they're naturals at it. I'm not a teacher either, not much of a teaching streak in me so, childrens stories that teach children to read and with some sort of moral lesson? Not gonna happen. No interest at all in doing that sort of thing.
Same thing with historical fiction that a lot of younger writers see as a gold mine these days. They figured out just target a large elderly group and write about huge events that they remember and play on their nostalgia. Like WW2, Elvis Presley, JFK and the summer of love. A lot of the time these historical fictions read disgenuine and contrived. I would say those authors are ripping off the elderly. Let the real deal tell the story is what I say.
So I guess that right now my target audience would be 24-50 years old, interested in action and sci-fi and war stories and just wants to be entertained without too much demand on them. Moviegoers and casual readers. I don't like to require my readers to emotionally invest themselves too deeply or be riddled so hard it drains their brain power. Perhaps someday I will get good at what I'm trying to do and actually meet that goal.