SPOILERS FOR THE OLDEST EXISTING LITERATURE: It's a story about a man trying to conquer monsters for the sake of timeless fame and glory, witnessing the death of his friend as a result of this quest, reflecting in his own mortality, trying to overcome death... and failing. There are other things going on with the story, the humor is repetitious and hard to embrace, and there are plenty of passages everyone is unsure about the meaning of, but this man-trying-to-overcome-mortality-and-failing theme is such a obviously human trope and it's clearly present in Gilgamesh. Compare and contrast to Ridley Scott's Prometheus.