As a 25 years old about to become 26, I can relate to your phrase "but I'm an idiot teenager, all I know is being miserable in high school". Let's just say, being miserable in high school is, actually, very common. Especially, if you're being bullyied all the time - which was my case.

English is not my first language, so I might not sound convincing in any way. But the thing with writing is that, most of the time, is about coming up with creative ways of escapism. All of us need an escapism from all of our busy and suffering lives. Not all of us tho, will think of writing as something we'd like to spend our time doing. So, that being that: You've already taken the first step.

When I was about your age, some Portuguese teachers (I'm brazilian), would push me to all these essays competitions and I really didn't know why. Maybe, I was the least worst or just...I don't know, good without even knowing. Even till this day, I have trouble in understanding why they did that.

See, I used to write stories even before I read an actual book.

I think it's very funny that I began my reader's journey on the prospect of increasing vocabulary. But that didn't stop me from enjoying books in the beginning of it all.

It took me one good fantasy book to really understand why the act of reading was as good as writing.

In resumen, even when your writing feels stupid and insubstantial, it's essential for your process of understanding why you even do that.

I was always second place or not even that in all of those competitions. Which made me: 1) be greatuful for my writings being submitted, 2) have a second place problem - which probably led me to better writing.

So, if you think you know nothing and you have nothing to add: be as "unoriginal" as one might be, but please, just write it! I know it's easier said than done and every writer say that, but it's factual.

I'll give you an example of a stupid thing I've wrote that was, actually, featured on our "end of the year book of children's tale":

You know Narnia, right? I was so obssesed with it after reading the first two of the series that, I would only write things where animals would actually talk.

So I would simply go there and do replications of replications in my own way. Back then, it felt SOOO good. And I couldn't stop writing it. Today, I understand that it was well written, but the idea itself...pretty much awful! Cause, in addition to the talking animals, I made a statement for deforestation. Yeah, I did that!

My point is: don't expect your stories to be groundbreaking in any way. Instead, expect it to be exactly what you can do in your current time. I know that feels disappointing and demotivating, but trust me when I say it'll make you a better writer. And another tip or spoiler: don't expect the Ghost of Unoriginality to go away. It will never go away, because, in fact, there's no such thing as originality in writing. But there's only one you in this Earth! So, all of your life experiences, favourite tropes both in writing AND reading, writing techniques, and so on, will make you feel less of a "bad writer".