How children play in their youth has lasting effects on who they'll eventually grow up to be. The article Innovative Practice: 5 Strategies for the Early Learning Classroom emphasizes how playtime creates safe spaces for youth to grow, develop, and build relationships. Playing with other children helps them interact with others prior to learning about social labels, breaking down boundaries as they become exposed to other kinds of people.
Children actually have a great capacity to teach each other about social norms and expectations, build lifelong relationships, and tap into each other's creativity. This peer exploration helps hone their communication and social skills.
Essentially, play immediately bonds a new group of strangers together. It's an early exposure to rules and how to act with other people, without social pressure and cliques influencing children's choices. And by becoming exposed to and growing comfortable with all sorts of people at an early age, it helps reduce social anxiety and enjoy healthy interactions later in life, while also honing many social problem-solving skills and good habits.