άνθρωπος is perfectly fine Modern Greek as well -- it's one of the hundreds if not thousands of words that have not changed (at least in spelling) in centuries.
'Lycanthrope' or the more recognisable and modern term for 'werewolf' can be translated into Greek as 'Λυκάνθρωπος'. As well as a few other 'were-' animals that can be translated on Google like 'Αιχμάλοτος' for 'weretiger' and 'Πραξικόπημα' for werelion.