Many people do live in Cape Horn, South America. Although not densely populated the population density is comparable to areas in Brazil away from the Amazon River and many other places in Latin America.
For thousands of years, The Yanomami tribe haved lived in the rainforests of South America The Yanomami people live in the tropical rainforests in northern Brazil and southern Venezuela in South America
Many millions of people do live in South America. Inhospitable places where food cannot be grown or there are no resources are small islands, deserts and mountain tops much as anywhere else. Otherwise it is a benign as any other inhabited continent.