I found the works of Jaques Valles and Terrence Mckenna on point. Not likely metal ships with aliens, but a manifestation of our collective consciousness befitting of the era we live in.
Come to think of it, from the ETs perspective, humankind could appear as being too different, maybe even too volatile for any kind of encounter to take place. Maybe to them, engaging with us poses too big a risk. Maybe we're a known as turn-offs....maybe we scare the shit out of them. And, maybe our earthly ways need to wise up. Who knows, but maybe once we reach a certain point in our evolution, we will be more susceptible to meeting other beings from space.
I think the general consensus is that there is some kind of binding agreement that they are not allowed to make themselves known in any kind of formal fashion. The sightings of random people are one thing, but coming down in full view of cameras and news crews is something else.
Honestly, I would wager if that were to happen, people would lose their collective shit and panic because of the general stereotype that has been associated with ET/Aliens. They are here to brainwash you, take over your body, kill/enslave you etc. Which who knows, their might be a faction out there that does wish to do this. I personally think that there are multiple species/groups and that it is about the same as it is with different groups on earth. Some want to just learn more, some want to own more. I find it hard to swallow that the only type of intelligent life out there simply wants to destroy whatever it finds.
I wish I could recite the different things i've watched and read that all kind of point to the idea that Humans are to be watched, not interacted with. But its been a couple years now, and there have been several. Personally it makes sense to me. Why on earth would you peek at us for thousands of years, but never fully make yourself known? To avoid going down the conspiracy path, and all that entails...
Personal opinion is we've had contact before. Do I think governments are hiding any alien activity, nope. Do I think governments are hiding information from us, yes.
Life has motives in what it does, why would another civilization waste so much just to swing by Earth. If they did come here, like many others have said, it wouldnt be for the best notions.
My opinion on when the normal person would be able to see something like your mentioned would be two ways:
Whatever started the original ideas of religion.
Or us finding life or signs of life on another planet. ( I like to think this would be the first way, done by a private company)
There are many that do claim that they have been visited, contacted, communicated with. There are some that claim that they can summon.
We have crop circles that some claim are forms of communication.
I could be wrong, but I think a "wow" signal has been received, and I saw mention that Tesla believed that he intercepted an alien signal.
Like you, I do not know what is true and what is not true, and it's very easy to dismiss all of it given individually we have no way of verifying any of it - but just because I have not been communicated with does not mean that others haven't been.
Einstein was correct on the whole speed of light thing perhaps.
Or, here's a thought, which might be the case: Aliens likely would not visit our planet in person. They would send something like a robot first. That's what we do. When we send a rover, we go to insane lengths to keep it clean and sanitized so as not to affect bacteria or fuck up research results.
Sending a probe/rover here, the aliens probably would not want to mess with any possible life here. When it's bacteria, that means sanitize, sanitize, sanitize. When it's intelligent life, it means disguise, disguise, disguise. Perhaps by making their "rover" so tiny we have almost 0 chance to find it, or so close to a living species that we would write it off as just another bird or bee.
It's probably the first explanation, but the second is more fun to think about.
Let's face it, some people don't want to believe. Even if grays would dance in front of their window, they still wouldn't believe it, because they are pathological skeptics (pseudo-skepticism)
Also, if you did see a gray dancing in front of your window - what do you do with that information?
Go and tell your loved ones? How is that going to improve your life.
Go and tell the newspapers, or youtube, or reddit. Oh hey guys, you'll never guess what happened to me last night whilst I was sitting on the toilet.
Choosing to ignore it and write it off as a halucination would probably be for the best in terms of an individuals mental health.