OK, let's say they are here.
That leaves many qualifying question to be asked.
How many reasons could we imagine, that would justify their presence?
A - We have to also expect that some consideration be given to the fact they they have, in fact, 'always' been here. That we have never been alone,
and that in one form or another, most paranormal events could be explained by their presence. Our efforts to categorize them as 'alien' may just be
the same humano-centric bias we would expect of a fledgling culture incapable of imagining themselves as less than the center of the universe.
B - The other possibility is that they 'came' here. This of course follows the logic that they are in fact alien to our world. But our world is
very poorly defined by us, generally speaking. We often fail to embrace the potential for an entire universe to exist right here, overlapping our
own. We 'logically' assume that some vast 'distance' was traveled to arrive here, when in fact, that distance may be a simple perceptual
limitation of our own understanding.
Maybe they are wondering why WE are here. We have imagined and made artful portrayals of stories where creatures began their existence as
manufactured beings who rose to self-awareness and thus achieved sentience. Perhaps the 'spontaneous' evolution of sentience via chaos and dynamic
systems is a marvel to them. Perhaps they are perplexed that we cannot reconcile their existence along with our own. Maybe they think we're cute
(or grossly fascinating).
Perhaps they are determining what 'use' we could have to their ends, but respect natural evolutionary processes so much that they don't wipe us out
in fear they will upset the balance of nature.
Maybe they are waiting for us to wake up....
From whence did they come? This would appear central to the answer. Is traveling to Earth a great effort, or expenditure of resources? Or was it a
casual jaunt down the galactic neighborhood?
Are they here to stay, or just passing through? Is it an invasion? An uplifting? A hobby?
Do alien conscious processes relate at all to anything to which we could relate?
Are we curiosities, objects, or phenomena they wish to catalog? They might be here to cultivate us... perhaps as friends, or food, or slaves, or
resources for exploitation of some kind.
The answers to the OP's questions may be frightening, comforting, or even completely unintelligible.
This was a great idea for a discussion!