To me, it refers to writing for the future. Writing to teach later generations instead of worrying about what the critics might say. I don't know a lot about Alice Walker's work, other than The Color Purple. But, I would say that just the simple fact that she was a black woman writing about other black women meant that she was ahead of her time. She was taking a chance and trying to teach future generations about life. She probably had a rough time being an author in her time, being both a woman and black were two strikes against her, so her works show a lot of courage.
Just my personal take! It's been awhile since I took any literature classes and since I don't know a lot about Alice Walker I could be wrong.
Edit: I totally disagree with the other person...the second part of the quote is not referring to children at all. It is refering to adults who are immature and act like children.
Me-Was an English Major in college