When you were a little kid, you probably went to your mom whenever you got hurt. If you just got a little cut, your mom probably put on some neosporin and a band-aid; if you got a bad scrape, she probably put on hydrogen peroxide and a band-aid. Basically, if you got hurt, your mom would put something on followed by a band-aid.
As we get older, we begin to learn to treat ourselves. Seeing someone else treat me when I got hurt was a big part of learning how, but it wasn't enough. I knew that scrapes called for hydrogen peroxide and cuts called for neosporin, but I didn't know why simply from watching. I also never saw my mom call the poison control center, but I knew that I needed to if I saw someone get bit by a poisonous snake. For that matter, even, I hadn't ever seen anyone get bit by a poisonous snake, so I had no actual folk knowledge derived from experience of how to tell if a snake was poisonous or not. First aid was therefore a form of folk knowledge and also a form of oral knowledge.