There was a King named Gilgamesh. He was hated, his kingdom prayed that he would die, so gods sent a beast named Enkidu. The 2 were rivals, until they fought and Gilgamesh won, earning the respect of Enkidu; the duo set out on a mission to lead.
They went to the forest to get wood for his village. They didn't know a demon Humbaba was the guardian of the forest, and wouldn't let them in. They fought a battle and they won, taking wood to the village and gaining the thought of a goddess.
One particular goddess Aruru noticed Gilgamesh's strength and loved him. He mocked her feelings. This angered the goddess. She sent down the bull of heaven to ravage their village, but they killed him and brought a new mission into place.
The gods were mad at both of them because they killed the bull of heaven. They could not kill Gilgamesh, for he was a demigod, so they slowly infected Enkidu with a disease which would finally kill him and plant a bitter seed inside Gilgamesh.
Gilgamesh, after realizing he too will die, set out on a quest for immortality. He first met with an immortal couple. But they said that it's something you earn and they would not help him. Gilgamesh would not stop until he got the answer he wanted.
Gilgamesh found out that if he got a plant, he would gain eternal life. Once he entered the sea he found the plant; so did a snake. The snake took the leaf. Gilgamesh drowned. But instead of being sad, he would die leaving a good village behind him.