What is man's role in the natural world? This is a question Defoe's novel wants you to ask yourself. Crusoe believes himself to be at the head of the social order. When he looks at the natural world, he sees its utility and the value of that. Instead of opining on the beauty of things, he notices production value. He also very much believes in the concept of private property. When Crusoe gets to the island, notice how he immediately believes that he somehow "owns" the island.
Humans should have dominion over the natural world.
Once you extend your labor to a piece of land, it is your property.