Writing kid-friendly characters seems super easy. They can be human, animal, vegetable, mineral, or all of the above, as long as they're over the top and have at least one catchphrase. Really, the only thing they shouldn't be is secretly depressing, because nobody wants to laugh at a silly cartoon dog or whatever, only to find out later that the dog did time for a fatal DUI. And yet, if you look into the official backstories of some of the goofiest characters out there, you will find that ...
Miss Piggy Was A Neglected Child With A Dead Father
The Muppets have gone through a lot of changes over the years. Cookie Monster used to work for IBM. Kermit used to straight up murder dudes. Gonzo used to NOT fuck chickens. But the point is that even before the Muppets were Muppets, they were still over-the-top and whimsical. Then there's Miss Piggy.
According to Piggy's creator, Frank Oz, he originally imagined the famous, anger-prone pig prima donna as, in his words, "a truck driver who wanted to be a woman." But after apparently deciding that the world wasn't ready for that, he came up with a different biography that would remind children that life is a series of gut-wrenching tragedies. He decided that Miss Piggy's father had tragically died, and that her mother had neglected her.
This never made it into any official Muppet media, but was apparently something Oz had in the back of his mind while portraying Miss Piggy. Meaning that whenever she was singing on stage, Oz was channeling the pain of her father dying in a tractor accident. When she was abusive to Kermit, Oz kept thinking about how her mother was mean to her because she had too many kids and was barely coping with her family situation, and how this caused Piggy to develop severe insecurities that in later life manifested as uncontrollable rage.