Humpty-Dumpty might have been an alien or cryptid. Maybe Rapunzel had shape-shifting abilities? And maybe there was something on the top of the hill that didn't want Jack or Jill from nosing-around, seems that someone should be familiar with their daily route to their water source. What are the chances of both falling at the same time? Smacks of a force-field. Don't get me started on blackbirds baked in pies. That's a Stephen King story right there.
I think we often try to find meaning where there may be none. songs for kids are often just silly. I can see that human nature would look to the biggest and strongest thing to sing about. We are often worried that the worst will happen and if we make light of it, our anxiety goes down. I do find it interesting that the phrase " LONDON BRIDGE HAS FALLEN", is code for when the queen passes.
There are so many ways to interpret things. Some things don't need to be and are just there. They say there are always truths behind legends/folklore/nursery rhymes/etc. In the end, it all falls onto each individual to come up with their own meaning until life presents a part of that truth to us to change our perspective. Damn...am i hearing that Captain Obvious guy again?