I don't think it's that unheard of. In nature there are lots of mimics that look and act like other animals, like mantises that look like wasps, non-venomous snakes that look like venomous ones, and the mimic octopus that mimics different kinds of fish. Also, is a ghost really 'alive'? 😋
Yeah, when I thought about mimic I dind't thought about real-world mimics at most mythology mimics that tries to look like an animal... It is a good implementation of "mimic trait"