Fashion serves a few purposed. Including (1) to sell people shit they don't need, (2) to prove that you are socially aware, which implies a whole host of personality pluses that appeal to potential mates, friends, and coworkers; and (3) to get laid, which is our meat half's main concern. I guarantee the guys wearing loin cloths are aware of each shred of clothings' telling details.
Who invented it?
I was actually hashing out relationship shit with the ex-love of my life a couple years back (10+ years after we'd dated) and he said that one of the things that he had always really hated about me was that I didn't spend a ton of money on clothes. I was like, "You dumped me because I was broke, in college?" And he looked confused. "Persian girls go into debt to wear nice clothes, you always wore the same dress to every party and it was embarrassing, my friends used to make fun of you." That made me smile. "So you dumped me because I was smart?" LOL. He's still in debt, I still wear the same dress to every party.