Notions about the origin of private property vs common property are kind of missing the point. People who want a rigorous economical-ethical system always want to postulate some sort of natural origin of property that makes a person “really” own something, or how no one can “really” own something.
But of course our notions about property are just human inventions, not natural law. We decide that Thag owns the moccasins he made from deerhide, because he killed the deer and sewed them together by the campfire. So they are his moccasins, and if anyone else took them without Thag’s permission, Thag would be justified in taking them back and perhaps smacking that person upside the head.
But that’s just a social convention. In a universal sense, Thag doesn’t own anything. The deer certainly has a bit more claim to ownership of its own skin than Thag does. And when we talk about the right to hunt at certain places, and to build a hut at certain places, and to sing certain songs at certain ceremonies, or to have sexual intercourse with certain females, things get even more murky.
The reality is that our current system of private property wasn’t handed down by God, or by natural law. It’s a hodgepodge of rules designed to satisfy human needs. We have rules about property because otherwise we wouldn’t be able to live. And if we dissolve all those rules as unfair we find that pretty quick guys who hold swords or guns that they don’t own start telling everyone else what they are allowed to do.
The notion that Bill Gates (or Microsoft stockholders) really owns the Windows operating system is as arbitrary as the notion that everything is owned by some nebulous “commons”. There never was any such thing as a commons, there was just a planet, and then some apes evolved, and then some of the apes started using tools. They didn’t own the planet in common, the planet just existed and the apes lived on it. And all our rule about whether Thag really owns the moccasins are just our attempt to keep people from arguing about it. So we say Thag owns them, even though we could say he stole the skin from the deer, and stole the water from the lake, and stole the firewood from the tree, and stole the air from the sky.
If Thag stole the moccasins from the commons, then every animal that ever existed lives by stealing, and every plant too. In one sense it’s logically defensible to say that animals steal from each other, and plants steal sunlight and water from each other, but it results in more confusion than it helps, because it assigns moral choices to entities that in most cases don’t even have nervous systems. Even if we’re only talking about complex social animals like wolves, chimpanzees, dolphins, or humans, using the word “stealing” is a way of begging the question.