I have spent over 200 hours volunteering with children, done through: teaching them writing concepts, taking care of them, and working with an established author to develop books for them. Would this be considered a hook for college apps?
This is an EC.
No. It’s a very good EC, but not a hook.
What are commonly called “hooks” are mostly not things that you can do or earn yourself; they are things inherited from your parents. The exception is athletic skill strong enough to be recruited by the college, where you do have to put in the effort to earn the recognition as such.
A hook is a reason why a college would want you in particular above all other similarly qualified applicants. Common examples of hooks include: recruited athletes (ex. the coach wants you to be the next quarterback of the football team), children of huge donors (hoping it will lead to more donations), people who may bring positive press to the college (ex. Malala). Few people have hooks and if you had a hook you would know it. As others have said, what you do have is a nice EC activity.