There are several reasons why it is important to study The Epic of Gilgamesh in order to understand world literature. First, it is one of the earliest preserved examples of literature in the world. Interestingly, it is the product of a written scribal tradition, rather than a purely oral one, and thus provides insight into early modes of literacy.
Next, it gives us insight into one of the great world civilizations, that of Mesopotamia. Its views of kingship and its duties, especially when taken in conjunction with the early Mesopotamian law codes, help us understand how ideas of justice, responsibility, leadership, and government evolved in early civilizations.
Finally, it shows us an early stage of Mesopotamian religion, which influenced the development of the Abrahamic religions (Judaism, Christianity, and Islam) as well as classical Greek and Roman religious beliefs and practices.