The historical significance of them is they show the acient beliefs of the people in questio, you can learn a lot about the greek's society and attitude in life by lookig at all the myths they made up, children's stories in our societies always have a moral right? well the morals of the myths from other cultures from other times show us what they thought of stuff......but why IS this in the advert section my misplaced friend?
If you look down the list of recent questions in this section, you'll find that someone already answered a similarly phrased question. Myths are a means of normalising certain behaviours and enforcing societal norms.