I think it's both fun and instructive to compare the whole of human civilization with an individual human in terms of lifetime and maturity.
I agree. But there's another great comparison which can make one's eyes water.
The universe is generally thought to be a little over 14 billion years old.
Now you can do the maths yourself, but if you made a movie which ran for exactly 18 years (and which runs at 25 frames per second) that movie would have 14.2 billion frames ... one per year ... geddit?
You'll have to wait until the last three minutes before you see humans throwing up Stonehenge and the pyramids ... and Neil Armstrong doesn't step out on the Moon until 2 seconds before the end.
Aliens are great for science fiction, but as scientifically minded person who rejects religious creationism and the need for a god or gods, I view the preoccupation some people have with the idea of super-intelligent aliens "watching over us" (for whatever imagined purpose) to be a surrogate replacement for a deity.
I have a great fascination and interest in scientific research into interstellar travel. So far our greatest minds have failed to find good reason to believe that faster than light travel is ever likely to be possible. The only sound theoretical idea is the
Alcubierre drive (which is the Star Trekian warp drive and Alcubierre acknowledged as his inspiration for his theory). However that remains a pipe-dream, due to a large number of theoretical stumbling blocks ... not least the improbable energy requirements. Even so NASA has been operating a warp-field detector so we may yet detect a passing Vulcan starship ... and let's hope it ain't the Klingons ... or the Ferengi.
On the other hand the technology for sub-light travel is entirely feasible and, at high percentages of light speed, time dilation means that ships' crews could travel quite vast distances without the need for cryogenics. Hell at 99% light speed you can get to the galactic core well inside a human life span. Of course more than 30,000 years will have passed back on Earth ... and another 30,000 years for the return journey. Sub-light travel will always be one-way, because who'd want to return to an unknown future; perhaps one where you would be outclassed mentally, physically, ethically, sociologically.
It is unreasonable to reject completely out of hand the possibility that ETs have visited us, but it is also unreasonable to suggest the possibility is anything other than extremely remote. Any sentient species which develops space travel would have to possess certain intellectual and sociological characteristics which we could recognise or surmise. I find it endlessly difficult to imagine a single logical reason why ET would ply all the way here just to study us from afar. We have so much RF pollution that they could make a perfectly good study from the Moon. If they had even a trace of something we might recognise as as ethics they would most certainly not to wish risk contaminating our ecosystems with alien organisms clinging to the shiny hulls of their flying saucers ... which begs the question: if they don't have that ethic it would suggest they come to conquer. If that was the case the "evidence" provided by UFOlogists is decidedly weird ... a race capable of doing what they are alleged to be able to do would surely have a better method of conquering than appearing to small groups of un-influential people in isolated places. On the other hand there are those who allege that our leaders are aliens in disguise. Poo! The world's leaders are such a useless bunch of twerps they simply
have to be human!