Question

The Epic of Gilgamesh is the world's oldest known

Answer 1

The Epic of Gilgamesh is the worlds oldest known literary work composed around 3,000 years ago in babylon.

Answer 2

The answer is that it is the oldest known piece of literature. It can't be anything else since there are many things that were already known as an oldest. For example, the oldest written law code is the code of Ur-Nammu.