FWIW, I'm a writer but I never thought of myself as a creative person.
OTOH, for as long as I can remember I have been a voracious reader and a dedicated student of literature. I adore stories! I see life in terms of narrative.
I never really liked those touchy-feely creative writing games. That's just not my style, and frankly, that stuff turned me off writing for years. Again, some people adore them, and more power to them! But there are ways to write without writing like that.
My background is in research and education, and I am a very analytical person. I like to learn things and teach them to people. Consequently, I like to write historical fiction. Probably the biggest thing that led me to writing was a passionate curiosity about people in the past and a desire to hear those people speak to me. I like to give a voice to history. That's a very different sort of calling than, say, poetry or adventure novels. Doing what I do, I don't have to think of myself as creative!
I do still have to observe, analyze, plan and construct though. I have to be able to describe how a spring day in Iceland smells, even if I've never smelled it.
If a child wants to write a novel, I'd ask what stories interest her and why.
I'd tear apart plots with her and put them back together so she knows what makes them tick.
I'd talk about psychology and encourage her to see the motivation behind people's actions: he didn't steal because he's evil, he stole because he thought the company owed him something. Note that people are not all-good or all-bad, but are justified in their actions in their own minds and are the stars of their own life-movies, even if they're just bit-players in yours.
I'd record dialogue around the house so that she hears how rarely people actually talk directly to one another, asking instead talking across one another or around one another.
And I'd encourage her to pay attention to her senses and describe what she perceives as specifically as she can.
Observe. Identify. Discuss. Repeat.
But mostly, I'd encourage a child who wants to be a writer to read. Read good stuff, read advertising copy, read classics, read junk. Soak it all in. When you have something to say, a real story to tell, the words will come. At least they did for me.
Oh, and the best advice I found when I decided to be a writer:
Writers write. Every day.
You can think about writing, talk about writing, read about writing...that's all fine and dandy. But in the end, unless you write, you're not a writer.
That kept me going in the face of many a blank page!
And that's pretty much everything I know (or think I know) about writing!
...Well, that and don't treat your words OR ideas as precious or sacred. You'll make more! You have to be willing to chop stuff up, tear it apart, throw it out, and do it all again if you want to make something worth reading.
