Social Roles (What are selves for?)
One answer, certainly, is that the self has to gain social acceptance.
People need other people to accept them in order to have a job, to have friends and lovers, to have a family. The self is one tool people use to accomplish these goals.
By learning how to act properly and how to conform to social rules and norms, people can improve their chances of social acceptance.
They change and adapt themselves so as to appeal to others.
A culture is a large system with many different roles, and everyone has to find a place in it (or several places). You cannot be a senator, or a nurse, or a parent, or a girlfriend, or a police officer unless you can reliably act in appropriate ways.
To succeed in traveling the long road to social acceptance, the person must have a self capable of all those jobs.
Many roles, such as spouse or engineer, can only be adopted after you have taken a series of steps.
E.g. Having a wedding, or getting a college degree with a certain major.
After you have the role, you must perform the duties that define it.
The human self is that it is flexible enough to take on new roles and to change roles.
E.g. A single human being, for example, might over the course of a lifetime work at mowing lawns, writing for the school newspaper, managing the swim team,and so forth.
Also, a person may perform similar jobs with several different organizations.
E.g. a professor who moves from one university to another but teaches similar courses each time