if Aliens had come to earth, we'd know. we'd all know.

The technological requirements for even getting to the nearest star (about 4.4 light years away) is insane. Then there's the material requirements, all sorts of other things.

The only real reason to even come here is us- or more broadly, our particular flavor of life in general. So xenoantropological studies, maybe xenobiology. maybe also making sure we're not the kind of psychotic dick-fucks that would nuke themselves a couple thousand times. (Five hundred or so, of which were atmospheric or above ground.)

Except that they would almost certainly have the technological capability to know that we have done so before ever considering coming here. (Seriously. the JWST is designed to look for certain compounds in exoplanetary atmospheres. among other things, sure, but it's capable.)

So, this fact would make any organization of body wary of even coming into our solar system. The rather reasonable question is what would we do with the tech if we found it- and frankly, the answer is probably "reverse engineer the technology enough to send it back out of rampant paranoia.". And we wouldn't be doing a braking burn. The missile wouldn't need a payload. the mere impact of an interstellar missile hitting a planet at such speeds would likely kill anything on the planet.

So we can come up with a few base motivations for aliens to come pay us a visit.

research is out- that would be done as remote as reasonably possible.

resource extraction is out. There's no need to come here when any other system would likely do. And it's unlikely to produce more resources than it costs. even if we're the resource in question.

Making peaceful contact is out, a la Star Trek: First Contact or Day the Earth Stood Still. We're not peaceful. We're psychotic dick-fucks who've nuked themselves.

pretty much, this leaves two groups.

you got the hyper-aggresive types that are here to wipe us out on the assumption we're too dangerous to let live. (Possibly, a default stance by the species,) and we know they're here because. well. they're wiping us out.

Then you got the Space Mormons; and you know they're here because they won't shut up about it.

There is, however, a subset of Space Mormons; where they turn into the Space Assholes when you reject them.