Where does the theme of colonialism come into play in Robinson Crusoe?
To me, this book shows this theme in the ways that Robinson Crusoe interacts with "his" island and then later with Friday.
What Crusoe does on the island is classic colonialism. He takes the island and tries to remake it in ways that make it resemble England and in ways that make it more useful to him. He domesticates goats, he domesticates parrots. He plants non-native species of plants and he brings dogs and cats onto the island.
When he find Friday, Crusoe immediately makes him a servant and teaches him to say "master" before anything else. He calls himself the king of his island.
So this is a story in which Crusoe's actions symbolize what colonizers do when they come to "new" lands.