Unstructured play is important for a child because it gives them a sense of freedom and control, and allows them to learn about themselves, what they like and don’t like, and even make mistakes without feeling any pressure or failure.
Children naturally, when left to their own devices, will take initiative and create activities and stories in the world around them. Sometimes, especially with children past the toddler stage, the most creative play takes place outside of direct adult supervision.
Free play in toddlers and young children most frequently involves spurts of gross motor activity over a period of time with rest in between. Most children are smiling and laughing, sharing ideas and seen helping their friends when they engage in freeplay, and it is reasonable to assume that their mood is improved during and after play.