Protection! Human skin is relatively unprotected from the elements including the sun. Most people do not live in tropical climes where living nude is possible. Even then, many people in those climes elect to wear clothing of some kind. White people in high-sun areas absolutely need to wear clothing and everyone does in colder climes.
I suspect that clothing became an object of power early in human development. For some time, humans endured the ice age and I suspect that the tribe leaders had the best clothes, the best furs. Keep in mind that during that period the human population dropped to no more than 6,000 people; all possibly living in one place and given the climate of that period, clothing would have been essential.
Had we simply stayed in east Africa and disseminated through the world, I tend to doubt that clothing would have been so universal. As time progressed, clothing, like body decoration or jewelry, helped to signify one's status in a culture. Today we use clothing not just for elemental protection, but as an identifier of job, social status, religion, authority, culture, and gender. Clothing is far more than simply protection and has been for a very long time.