Actually, there’s a fair amount of evidence that we are, as a species, less intelligent than we used to be. Early humans, around the time we discovered farming, had to live on their wits from day to day, and there was no respite. As Darwin used to say, ‘use it or lose it’. (Well maybe he didn’t, but you get the point). Most of the brain mass/structure we have now is the same as we had then, but we used to use more of it. Which is presumably why it’s so much bigger than it needs to be now. (Yes, as evolution progresses, human brains will probably get smaller.)
Intelligence has nothing to do with what you know. It’s how quickly you can figure stuff out. Like, for example, if thrown into a completely unfamiliar and dangerous situation, like in the middle of a forest in Canada, 500 miles from the nearest help, naked, with nothing but a rock. Could you survive? Could you prosper, raise a family, pass on your genes?
(No jokes about trying to make a family when you’re alone please)
“No-one ever seems to consider that we actually be the first 'intelligent' life in the Universe - after all, someone has to be first....”
Actually that’s statistically unlikely. Life on earth arose almost immediately as it cooled after formation. Even before the bombardment phase had ended. In fact it seems to have been wiped out and independently started again and again. To the first few waves of living organisms, oxygen was poisonous! This tells us that where a planet is habitable, life can easily and quickly arise.
But the earth (and the solar system) formed well into the evolution of the universe. About 4.5Bn years ago, when the universe was about two-thirds of its current age. So there must have been many other planets that were formed, (and became habitable) long before the earth. And of those many other life bearing planets, some must have prospered, since planet-wide sterilisation events are so unlikely (once the solar system has settled down).
So the answer to “are we alone in the universe” is almost certainly “NO!”.
Unfortunately, so is the answer to “will we ever meet any of them”.