My interpretation differs: it’s both, and both pave the way for each other...
It’s a riddle, a symbol, and an analogy. 666 is the number of a man. What man? All men, all humans. It’s the other side of our nature. We are a dichotemy, the spiritual side vs. the other; both at odds with one other. Which do we pay attention to? Secular humanism claims there is no spiritual side, only the beast. There are many facets of that serving to drive us away from our spirtual selves, all of them very powerful tools in the hands of others intent on minding the business of anyone but their own.