I’ve seen this before as well, but as a parent with two kids who loves to wonder about this very question, I can assure you a five year old (a kindergartener) is much, much smarter then a dog. They are filled with ideas and imagination, math / reading / writing capability, creative drawing and of course a massive spoken language advantage. Sure, they’d still lose in a fight, but then they’d (correctly!) tell their parents what is happening and we’d call animal control :)