These things have an intelligence level significantly beyond our own. And probably have a lifespan much, much longer than ours.

These things have a purpose here and serve an authority of some type, they have rules or laws which they are bound to. Their behavior suggests every part of that. They are not controlled by the same fears that we are but instead some authority which they rarely go against. I don't think that our existence has much to do with their presence here currently, it may have in the past or in the future but not currently.

I do think that sometimes they make their presence known to some people for some sort of purpose related to that individual's life history, kinda like a "nudge" to push you in a certain direction to obtain some type of comfort or enlightenment.