How do child labor laws work?

[Questioner]

As far as I'm aware of, a child participating in athletics, such as school sports, or artistic or creative activites such as theater isn't considered a violation of child labor (such as in the case of celebrity child actors), or requires a lot of physical exertion. (Obviously school requires some degree of "work" or "exertion" as well).

I'm curious how child labor laws factor into this, or why if a child had parents permission to work for a company and wasn't "forced" or coerced in any way, would this be in violation of any state child labor laws? Or is the exception solely for sports, arts, and so forth?