Carrie wasn't the first book Stephen King published. It was, in fact, his third--that is, if you don't count all of the others.
Because I'm sure there were.
How about all of the stories Tom Clancy wrote before Hunt for Red October? Or the stories J. K. Rowling wrote before she came upon Harry Potter? A Time to Kill I'm sure wasn't John Grisham's very first attempt at a book.
Why is it we never hear about the trunks of failed stories our favorite writer has stored in their attic? The ones they wrote before they were published?
We only hear about the successes. And, because of it, everyone thinks you need just one book to put you on the map to publication. I don't know how many times I've heard, "If I can just write this one book, I'll be set for life." Not true.
Brandon Sanderson, acclaimed bestselling fantasy author, has publically stated that he wrote 12 novels before he was ever published--that's impressive, dude! And do you know what he was doing with those 12 novels? Learning.
Learning the craft of writing by . . . well, writing.
And that's what all of the other writers were doing too.
So write and fail. And keep failing. Because at least you're doing something. Then, one day, when your skills are honed like a razor-sharp knife, you will be ready . . . and published.