School systems should base their curriculum not on the idea of separate subjects, but on the much more fertile idea of disciplines... which makes possible a fluid and dynamic curriculum that is interdisciplinary.
There's a wealth of talent that lies in all of us. All of us, including those who work in schools, must nurture creativity systematically and not kill it unwittingly.
You can't be a creative thinker if you're not stimulating your mind, just as you can't be an Olympic athlete if you don't train regularly.
Whether or not you discover your talents and passions is partly a matter of opportunity. If you've never been sailing, or picked up an instrument, or tried to teach or to write fiction, how would you know if you had a talent for these things?
Creativity is the process of having original ideas that have value. It is a process; it's not random.
Now the problem with standardized tests is that it's based on the mistake that we can simply scale up the education of children like you would scale up making carburetors. And we can't, because human beings are very different from motorcars, and they have feelings about what they do and motivations in doing it, or not.