There are many types of myths, and from nearly every place in the world! Each country, continent, and culture has different myths, with different gods, humans, and other creatures. Usually, a myth exists for one of three reasons: to teach a lesson, to explain the unexplainable, or to provide entertainment.
Many lessons are taught with myths. There was a myth about a lady who was playing in the stream with her child. When she plucked a flower from a tree branch, it turned out that the "tree" was actually a nymph in disguise - and in its anger, it turned the mother into a tree herself. This proves that Greeks treasure nature, and detest anyone who kills or disfigures plant life. The myth teaches us not to hurt nature, but to appreciate it how it is instead.
Another reason myths are passed on is to explain the unexplainable.
Creation, for example. No matter what anyone says, there is no proof of how Earth was created. So, people made up ways to explain it. As one African myth said, there were always animals, water, sun, the moon, and etc in the world. One day, a chameleon heard a strange sound inside the trunk, so he cut it open - and out walked the very first two humans. That's just one of the very many myths that show how the Earth, or certain things in it, came to be.
Everyone loves to be entertained. One way to have fun is to read myths - and that's exactly why some fables and myths were created. Many Greek (and other) tales have no purpose other than just stories, and that's fine. Most myths are like that, they just tell stories.
In conclusion, myths are told for three different reasons:...