I'd suggest starting with a small mobile iPhone or Android app. Make a little bit of side money while building a portfolio you can use to your advantage later.
Why not? The point is to learn. Good software engineering skills take years of practice and experience.
One good experience to have is finding out that something you enjoy building might not be something people enjoy using.
Personally when I was your age I was creating websites. I made a book search engine, and a geoip enhanced amazon affiliate ad system for easily adding affiliate ads to blogs and websites. Both achieved some minor success, although they eventually got banned by Amazon (the book search engine because I was scraping Amazon content, and the ad system because it got adopted by a lot of spammy content farmers because it was a highly effective way to monetize Google traffic, so Amazon blocked my API access).
So the ultimate success of my ideas was minimal, but the experience I gained from those two projects got me a great job at a startup that has led me down a very successful career path so far.
When I was closer to that age, there wer 16yo running major pirate software networks, art groups, bulletin boards and even developing related software for the fun of it... if someone finds it useful, awesome, if it solves a problem you experience even better.
It doesn't have to be widely used for the experience to be beneficial, and to make a little money off of it.
Even if you truly had the merits - how could you possibly be seen across the noise?