I've seen a gameplay of Inside from a YouTuber (jacksepticeye) and came up with an interesting theory. I first start forming this theory at the start of the game when the boy sees the truck full of people and then runs after it. Then, as you progress through the game, the boy is able to have other people help him throughout the puzzles. Then, when the boy gets the ability to breathe underwater, the fish follow him. And at the beginning, the chicks follow him. The people who try to kidnap the boy in the beginning, the aquatic humans, and the pigs and dogs are all against him. So what does this mean? Well, according to my theory, the boy decided to rebel against society, and slowly gained more followers, starting with the chicks in the beginning. And as he moves throughout the game, he gains more and more followers as they see his point and rebel with him, as he's the "face of change" and the "voice of the people". And the people who conduct the experienments, the aquatic people, the pigs and the dogs are all trying to stop him from turning society upside down. But that's just my theory.