This. Do people seriously think we have real werewolves and vampires running around in village? Come on, it's obviously just meant to be heavily inspired by these things. The explanation at the end of the day is going to be a virus of some sort. This is Resident Evil. And the series has always been inventing new creatures from different virus strains, this is nothing new.Zombies in the classic games of the series are not the real living dead, because the t-Virus is not able to resurrect the dead. These enemies are so called because they just look like George Romero's undead, but they are not undead. They're not real zombies. It's the same with Lycans, who look like werewolves but aren't really werewolves.
If I'm remembering correctly, I believe the explanation for the graveyard zombies in those games were that they were people recently buried who were in that "comatose" state of becoming a full on zombie and mistaken for being dead. Thus they were buried still technically "alive" but infected by the T-virus.I’m sure certain strains of T-Virus can resurrect the dead as seen in the graveyards of RE3 and CVX, with T-Alfred being the one that leaked on Rockford Island, correct me if I am wrong.