The Christian is a Platonist about one man, Christ: he pre-exists both his conception and his birth. But there is no Platonism about any other human. The rest of us enjoy no Platonic pre-existence. We are literally nothing until we are conceived. One could say that orthodox Christians are anthropological exceptionalists with respect to one man. And he is indeed a man. If he is fully God and fully man, then he is fully man.