Taxonomy is a human invention to create artificial categories of groups of animals with shared traits. Monkeys are in one group because of certain traits, and apes are in another. Essentially, apes, monkeys, and humans share a common ancestor. This also applies to apes, monkeys, humans, horses, donkeys, dogs, zebras, lions, and so on that are all mammals. All mammals share a mammalian ancestor. All land creatures share a common ancestor as well, but further back in time of course. All animals that breathe or need oxygen share ancestry. And so on. In a way, we could say we're all bananas because really far back, we do share even a life form (multi-cell eukaryotes) as well.