[@Clocktowerechos] I'd say centuries, but for the mortals, they seem immortal. There would be only a few of them (few dozens at best in the world), but they are centuries old and mostly reclusive, as in staying out of people's sight sometimes years or decades at times. Of course, some might seek more contact or influence with the humans and others.

And concerning the living god, as you mentioned a monster, Frankenstein's monster came to my mind. A man or woman who came back to life thanks to some "unholy" magic or experiment.