Many nursery rhymes were made up to poke fun at real events and people.
Baa baa black sheep is about taxation. One third of crop to master, one third to church and one third left to live on
Humpty Dumpty is about a real cannon that accidentally fell off a castle wall in Scotland.
The grand old Duke of York really did march his 10,000 soldiers up and down.
Mary, Mary, quite contrary describes the court of Mary, Queen of Scots.
Little Jack Horner was a real bishop who helped himself to some plum properties.
London Bridge did burn down and Ring a ring of roses describes getting the black death.
It varies. Many dealt with dead-serious adult and even political topics- such as the Black Plague (Ring around the Rosey) and ashes, etc implying cremating bodies and tossing ashes off the roof, or down the drain. Mary Mary, Quite Contray was political poking fun at Queen Mary I of England, who has been much maligned as the prototype for the phrase (Bloody Mary)- the sad if not tragic queen reigned for only five years and was deeply religious. she was only (In Office) from l553-l558, but it is amazing how much bad rep got around. Other Nursery Rhymes poked fun at other aspects of politics, decaying infrastructre(London Bridge is falling down) as I see it if its the more modern one- correctly called Tower Bridge, it is folding up- it"s a Bascule bridge!) and so on. then there are the funny modern ones such as the maneuvering watch which concludes: One to watch, One to Steer, and ATwo to fetch a can of Beer!again not very healthy!