That's the easy answer. The hard answer isexplaining how we could possibly learn anything true from a series offalse statements. One answer is that good works of fiction use falsestatements to describe deep truths about human nature, emotions,relationships, morality, and the meaning of life. They do so by creating a world of characters and events that does not actually exist but that shares enough common features with our world that we can learn from them. Most importantly, the fictions may share the deep (and general) truths about human nature, etc. with our world, and they may do so because the writer has a deep understanding of these truths.
Fiction also explores the boundaries of the possible and teaches us to think about these possibilities. Philosophy often works in this way. By considering what is possible but not actual we learn something about our world and ourselves. Science fiction and philosophical thought experiments sometimes differ only in that the science fiction tends to be better developed and better written.