Without school, the world would be very different. People wouldn't be as educated, technology would be less developed, and people would have to learn to feed themselves. How would these things affect the world, though?
To start, without school, most people wouldn't be as educated. People would never have gone to school to learn things, and something one person knew would probably be completely different as what other people know. They would learn from experiences rather then in a classroom, and most people wouldn't know about science, math, or how to read. Without going to school, people wouldn't learn how to write either, so there wouldn't be anything to read anyway. In addition, without school, people might not even know how to speak a language, and their communication would be very basic.
Next, technology wouldn't be as developed as it is today. This includes computers and medicine. Without the technology we have today, life would be very different. We wouldn't have devices to use to communicate with other people, and if someone did know someone that didn't live near them, they would have to travel to where they live to visit them. Since people wouldn't know how to read or write, they wouldn't be able to send the person they know any mail. Also, since technology wouldn't be as developed, there might not even be paper to write on. Without the technology we have today, people wouldn't have anything to entertain them. No movies to watch, no video games to play, and no books to read.
Last, people would have to learn how to feed themselves. They could hunt various animals and feed themselves with meat, or they could plant corn or beans and harvest it. They could collect berries and natural growing fruits and vegetables to eat. People wouldn't have manufactured food to eat like we have today, like chips, chocolate bars, or candy. People would probably get sick or die because the foods they eat wouldn't always necessarily be fit to eat, or be healthy, or the meat they eat might not be thoroughly cooked. Without the medicines we have today, people that get sick or get diseases would end up dying, and the average lifespan would be much shorter then it is today.
To conclude, if there had never been any schools for people to attend, life would be very different. People wouldn't be educated, we wouldn't have the fancy technology we have today, and people would have to learn how to collect their own food and feed themselves rather then depending on other people to make healthy food for them. Because of this, the average lifespan of a person would be lower then it is today, and people would die younger then they do today.