What's the theme of narcissus and echo

The theme of this myth is to not be caught up in ones self and to not be vain.

The word narcissistic, meaning focused entirely on ones self, comes from the main character’s name.

The first thing that the story of Echo and Narcissus teaches us is to beware the trap of vanity or self-adoration. Basically, don't go around thinking you're all that. Narcissus is so attractive that he practically has to carry around a spear to keep the girls away. The problem is that he knows how attractive he is.