how does the opening scene of Bruno and his friends represent their innocence

The movie opens with the boys running free and playing in Berlin. In the book, a glimpse of Bruno with his friends doesn't come in until Chapter Two. It describes how Bruno used to walk home from school with his friends Karl, Daniel, and Martin. They would pass people sitting at tables outside, eating and laughing. This innocence is typical for most children (not all). The freedom to walk freely outside..... to see people..... to move about unafraid because you've never had an experience to cause your fear.