The last human.

Humans created genetically modified humans with animal genes resulting in what they called "semi-human." Human-looking creatures, but with ears and tails for their amusement and to make them cuter and more attractive to human eyes, consequently, demi-humans were sold as pets and on many occasions were cruelly treated as sexual objects or mere slaves, in general, humans consider demi-humans a product that they themselves created and consider them their property, that was until the demi-humans rebelled against their creators unleashing a war of extermination where humans had the advantage and demi-humans suffered unimaginably in extermination camps around the world, fortunately, for the demi-humans a disease, created by humans, escaped from one of their laboratories: it was a viral weapon designed to kill demi-humans, but it ended up killing the very humans who created it which led to the demi-humans being free from human tyranny. It's been 2000 years since those events and there are no humans left on earth anymore, but the elderly demi-humans keep telling that story from generation to generation, the demi-humans were unable to create civilizations as advanced as human society once was, instead they live by collecting scrap metal created by humans 2000 years ago and living in small communities. The large human cities today are dangerous ruins that are covered in nature, the large human skyscrapers are dungeons in which interior forests grew and which birds use as cliffs to nest. Going to those cities is still dangerous for demi-humans, not only because of the risk of collapse, but because there are still functional autonomous robots that were created by humans and that will kill any demi-human they see.