What is Gilgamesh about?

Gilgamesh was a King of Ur, he was 1/3 god, 2/3 man. He is devastated by his friend Enkidus death and doesnt want to die also, so he sets out on a journey for immortality. Someone tells him to go find a certain flower that if eaten will give you immortality. HE finds the flower and is going to take it back to his people to share but a serpent takes it on his way back. He goes to the gods to ask for immortality, and a god, tells him that if he can go without sleep for 7 days and 6 nights, then he can become immortal. He fails and falls asleep on the first day, and stays sleeping for all of the 7 days. When he gets home, he is not able to live forever, but he writes down his story, so his story will live forever..