I began dabbling in writing at a young age and my early stuff was very poor, but still a necessary part of the evolution. I was just having fun daydreaming about space and fantasy lands and stuff, no real effort at producing coherent stories. I drew a lot as a kid, so sometimes I'd write little stories about the stuff I'd drawn, or the other way around.
It seems I've always been bouncing back and forth between novels and short stories. Started with shorts (they were school assignments) then started tinkering with a novel when I was, oh, in my early teens somewhere. I spent a ton of time in that world, building it up, but it was more of a super elaborate long-term daydream and not such a lot made it onto the page. Early onset Worldbuilder's Disease, you could say. This first effort at a novel was... inelegant, but some of those ideas have stayed with me and been repurposed in later works.
By mid to late teens I was back to short stories. Warhammer 40K fanfiction, mainly. This was the first work I actually took some pride in. This phase lasted a good few years and included plans for a novel that never really got started.
In my early twenties I was back to that novel I'd abandoned years earlier, and it gradually morphed into a completely different story. Hadn't really found my feet as a writer yet and I was still sanding down the rough edges of my English (some of my early stuff was in Norwegian). Things didn't flow naturally, my prose was stilted, and I kept obsessively rewriting paragraph. Not a lot of progress made that way. Ultimately nothing came of that novel (yet, I still hope to pull it off someday) but I evolved plenty from working on it. New ways of thinking about story emerged.
Then I did barely any writing for maybe half a decade. Kinda imagined my flirtation with that form of creative expression was over. Did lots of drawing and painting in this period.
Cue late twenties. I started writing this short story, which I'd brainstorm on a piece of paper during lulls in my office job. And something loosened. My imagination was on fire and the ideas just poured out. I wrote without that old fear, without the compulsion to make each line perfect before moving onto the next. That story had flaws and plenty of them (it has since been rewritten several times, and now forms the basis of a novel series) but by gosh, it was effortless and inspired stuff. Maybe the first time in my life I felt like a real writer. And for the next several years I churned out many short stories, left a mountain range of unfinished WIPs in my wake, exploring different genres and styles and voices and character types. Possibly the biggest period of growth.
Now in my mid-thirties I'm once again doing novels pretty much full time. I'm at my most confident and creative ever. I still have much to learn, and calling a sense of mastery is perhaps too strong, but I feel competent, certainly. Much of the time things just flow beautifully and I don't get snagged on needing things to be perfect right away. I've gotten better in every respect, but the most important bit of growth is that I've learned not just to enjoy the process, but love it, to write from a place of passion rather than goal-oriented tension and compulsive attention to detail. My work feels so much more alive and juicy than ever before. Also, I've learned that I really enjoy writing relatively lighthearted and rather silly comedy stories. Found my voice, you could say, though I've other voices I like breaking out on occasion.