Childhood can be difficult. One is gaining all kinds of abilities very rapidly. At the same time, one is being constantly instructed in when to use them or suppress them. And then one learns about hard and final limits, such as never being able to fly.
Child’s play provides an outlet for all those distressing complications. Your toy figures can fly or turn invisible. Characters can yell and fight. Buildings can go up in one instant, get destroyed in the next. Limits are non-existent.
When an adult plays, it can be amazing how much forbidden stuff a child can work out. Characters are allowed to say and do things already taboo in polite society. They can hate school, refuse to eat vegetables, act out tensions with adults. A keen grown-up observer is constantly educated and entertained.
The more fortunate among us never completely abandon childhood outlook. We can still build castles in air, even if now they are dreams of ambitions. We can imagine outcomes to our anger forbidden in real life. And, most important, we can occasionally escape all our limits and wallow in the wonder of the world.