There were people on this island before Prospero came. Caliban is one. His mother was a witch put ashore here, and he was born on it.
At first the three of them lived together. Caliban showed them where the springs were and which fruit could be eaten. Prospero and Miranda taught him language.
Now he carries logs. He walks with a load on his back, cursing. People who shared a house are divided into master and servant.