Initially they were pets. When I was 10, we were visiting family down south. One of my uncles said "If you can catch it, you can keep it". Well that occupied my time all day. 6 hours or so I was stalking chickens. Mostly game, with some bantams scattered around. I cornered a little black bantam hen up against the barn, and actually caught her. Brought her right in the house to show off. Everyone laughed. My uncle says "Well what in the world are you going to do with one lil 'ol banty hen?"
My parents took us to a flea market the next day, and I bought some little black bantam chicks. The hen was nice enough to take them on and was nice to them. We converted the rabbit hutch to a coop, and every time I saw chickens, I'd add another breed. Had up to 53 on our urban lot, before it was trendy. Cochin, Frizzle, Silkie, Rosecomb, EE, Seabrights, OEG, mix breeds, whatever was cute. Piles of little bitty bantam eggs. Got my first incubator the next year. They free ranged, because we were the last house on the road and it backed a park. Now one street over, the last house there has peacocks and everything.
Since then, I try to always have a handful of layers. Right now I have 5. Great pets, breakfast too. I've only ever eaten the mean roosters. Haven't been able to eat a hen.
Now I have an appreciation for the rare breeds. For a couple of years now I've been fooling with shipped eggs and getting birds I can't find locally. The next breed will be Legbars. Haven't had any blue layers for awhile, been on a Marans kick. Though I have an opportunity for some Swedish Flower eggs locally. Always so many choices with chickens!