"I could write a book!"
Many people say it, and some of them actually follow through. And I genuinely believe that the following statement is true: Anyone who actually sits down to write a book CAN write a book. Have a beginning, middle, and end with a discernible story arc? Is it over 65k words (50k is only "long enough" for Middle Grade, so anything shorter only counts as a first draft with LOTS of stuff to add)? Congratulations, you wrote a book!
Now here's the tough question: How good are you at editing? I may have heard people say that once the "creative process" is over, it's time to start editing. But if you aren't a creative person, you won't be able to edit or revise creative writing. Yes, there is a mechanical science to editing, especially when it comes to grammar. But the creative writing process REQUIRES revision. Unless all you want to do is write a book, stick it under your bed, and start over.
So, can you write a book? Maybe. If you sit down and work at it. But can you PUBLISH a book? With self-publishing as a truly viable option these days, you could get published. And a few people may even buy it.
The success, however, lies in the hard parts of the creative process. The revising, the editing, and then THE MARKETING!
I imagine creativity accounts for close to 50% of the entire publishing process on an author's end. But just because something isn't directly related to writing or revising, that doesn't mean the creativity can end. In fact, the only places you DON'T want creativity are in contract negotiations and dealing with money. Be as mechanical as possible with those to avoid getting taken advantage of (with contracts...though that's not as common as the horror stories might imply), and to avoid PRISON or hefty fines (with money and taxes).
Everything else requires one or another level of creativity. AND WORK. VERY HARD WORK!!
I cannot emphasize that enough. As fun as the creative process is, sitting down to finish the first draft is ONLY THE BEGINNING. And even that takes work.
It's right there in the concept: the creative process. Process. So process that, then get to work.