To clarify, I didnt mean to sound like everyone making a claim that aliens exist are wrong, mistaken, lying or have alternate motives, just that human behavior will dictate that that is the case for many of them. As you said though, only one of them needs to be right, which is entirely possible.
Understood. I was sort of just saying that regardless as I don't know your total beliefs and didn't necessarily mean to infer such upon you either.
For me personally though I'm not convinced yet that another life form has visited our planet. Regular space travel just seems implausible to me at the moment given that traveling at the speed of light would still take an alien decades to centuries to reach many of the closer stars within our galaxy.
I think thinking about space travel limitations considering what current unclassified known human technology displays is perhaps not the best way and there was a time when many people thought humans would never be able to fly, it wasn't that long ago really in the grand scheme and I think someone or some group of humans may have even already developed technology that is far more advanced. Some say the secret technology is usually like 30-40 years in advance of what the public gets and in some cases maybe it's even much more than that, and maybe some never gets released at all.
All the stuff we see could certainly be human tech or time travelers or something else human caused, though I think it's highly likely we've had visitors from elsewhere already and going back thousands of years if not longer, maybe even millions according to what some ancient traditions and belief systems propose.