They JOINED TOGETHER, to make a larger version of themselves."
Because no natural or man-made object could ever do something as amazing as that.
I saw a light in the sky. I don't know what it was.
And you know why that is more amazing than your account? Because my account doesn't involve stars and clouds being mistaken for aliens. Seriously, have a look at your account again:
I saw an unusual cloud formation... [description of normal cloud behaviour]... stars were just beginning to appear... a 'star-like' object to appear at...
I mean, wow. An object in the sky that looks and behaves like a cloud, and an object that looks like a star appearing among the stars. Amazing.
Edit: I'd just like to add that my problem isn't with your experience at all, it's the conclusions you draw from it. Notice the difference between your response to your experience and my response to mine. In your case, you saw something you can't explain. From the way you describe it, it doesn't sound in the least bit impressive, but that is not the point. The problem is very simply that you can't explain it, and neither can anyone else, because there simply isn't enough information to go on. You were there, but human observation is notoriously unreliable, and human memory even more so, so what you think you saw, no matter how much you believe it, is very likely not what actually happened. It may be an optical illusion, it may be misinterpretation, it may be hallucination, it may be false or distorted memory, it may simply be made up, or any of a huge number of other possibilities. Without other witnesses, recordings, replications and so on, it is impossible for anyone, not just me, not just you,
anyone, to ever know what this actually was.
This is where my response to my sighting comes in. I saw something. I can eliminate most explanations people can think of. The conclusion is not that I saw something amazing, it is simply that I saw something and can't ever know what it was. It was probably entirely normal, but since I couldn't study it properly at the time, I can never have the data to know for sure. This is what you should also be saying. I can't debunk or explain away your experience because I simply don't have enough to go on (although from what you've said so far I'm considerably less than impressed). But neither can you draw any conclusions from it, because
you don't have enough to go on either.
The problem that you, and so many believers in UFOs, bigfoot, psychics, and so on, have is that you appear to really hate uncertainty. When it comes to things like this, "I don't know" and "Not enough information" are not only acceptable answers, they are often the only honest answers possible. You cannot jump from "I saw something once" straight to "There are obviously non-human intelligent lifeforms living on the Earth flying far more advanced aircraft than are known to exist, or even be possible". That's not just a big leap, it's strapping on a rocket pack and launching yourself from a cliff. Your experience may be everything you claim it to be or it may be absolutely nothing, either way, the conclusions you reach from it are utter nonsense.