What do you think Lois Lowry meant when she said this book is for all the children to whom we entrust the future?
Throughout the novel, Lois Lowry depicts the horrors of attempting to create a utopian society, where individuals are completely safe and live in an extremely structured community. Lowry depicts what life would be like without independent rights and illustrates the power of conformity. In the ever-changing modern world, certain government officials or citizens may subscribe to the belief that limiting individual rights will result in a more stable, safer society. However, Lois Lowry argues that ensuring that each citizen is safe and comfortable has significant negatives attached to it. The Giver offers a look into the negatives of a utopian society, where individuals have no independence and miss out on numerous experiences. In her dedication at the beginning of the novel, Lois Lowry is speaking about the importance of educating the youth, who have the power to shape the future. The novel serves as a warning to the dangers of limiting individual rights and conforming to society's image in the hopes that children will consider the negatives attached to enforcing such laws in the future.
The line you mention is the dedication of the book. I think that the author dedicated the book in this way to show that she means the book to be a warning to people. She hopes that children will read the book and be inspired to prevent our society from becoming like that of Jonas's community.
In this book, the author is warning about the dangers of trying to make our communities too homogeneous. She is trying to show that making everyone be like everyone else (and taking the danger out of our lives) is something that will make us less human.
By dedicating this to "children" she is trying (I think) to emphasize that the book is meant to tell us what is valuable in human life and society.