There are two very important ways in which Gilgamesh and Enkidu benefit the society of Uruk.
First, Gilgamesh is a great city builder. He built wonderful ziggurats, walls around the city, and orchards. In short, he created civilization for the people. However, there was a problem. He was an unjust ruler. For example, he raped any beautiful women he wanted. So, rather than protecting his people with justice, he preyed on them whenever he wanted. This is where Enkidu comes in.
When the people cried out to the gods about the evil ways of Gilgamesh, the gods heard them and raised up a powerful wild man, Enkidu. When Enkidu heard about the ways of Gilgamesh, he went to confront him. They fought and in the process they became friends. In this friendship, Gilgamesh became a better ruler.
Based on these two points, we can say that Gilgamesh gave civilization to Uruk and Enkidu made this civilization just.