Charectoristics of a good fairytale

The main element usually present in a fairytale is that the story must have a moral principle that the readers of the story can learn. Since mostly kids read fairytales, this is usually somebody making a mistake that hurts them later on, and this makes the child learn not to make that same mistake.
Another common element is that the main charectors are usually kids. This allows the child readers to relate to the main charector and hammer in the moral of the story even more.
The third and final necesity is that the story needs to be interesting to a four year old. A child would not want to hear a fairytale about the stock exchange. They want to hear something that they will be interested in and will remember without thinking about it. If a fairytale does not follow these principles, I do not beleive that it is a good fairytale.