If Margaret can do it, there is no reason, in Ellie's small yet active brain, that she should not also get to do whatever thing it is. Sadly, sometimes she is not quite capable of the things that Margaret is doing.
Actually, frequently, she is not capable of the things that Margaret is doing, and the sight of an Ellie lying disconsolately on the floor sobbing "I want scissors" is one of the saddest sights to see in all the world.
Also funny. But mostly sad.
Anyway, often on our trips to the park, she sees Margaret doing something that looks awfully fun, and then when she comes to do it, she discovers that universal truth about how your actions are somewhat limited by the length of your arms and legs.
And then, looking to me for help, she discovers the harsh truth that I am not the person to look to when what you want is longer arms or legs.
So she goes back to contemplating the things that she cannot do. It is very, very sad.
Someday, kiddo. Someday. You'll get there. Probably by next summer. And then no playground ladder will be safe from you.