Humans have no real AI and certainly no super AI yet so your jumping the gun there.

The universe is really big and full of obstructions, not super old compared to Earth.

We could still easily be one of the first successful intelligent species. We have no metric to judge our ability to guess how common intelligent life really is. Intelligent life might kill itself off about at the level of development we are now or perhaps most intelligent life does not get as intelligent as rapidly as humans did.

Sending radio signals that far and having them recognizable might also be much harder than we are imaging unless your fairly close.

There is no huge mystery here in the sense that we don't already have good enough explanations, we just have no way to check our work and be anywhere near confident in our guesses when where the only example of intelligent life of even a habital planet.

Maybe a better question to ask is why would we think we know that much about the universe when we haven't even found a single other really habital looking planet.

As awesome as the big shots of nebulas and galactic clusters look, when we try to zoom into something as small as a planet we get little more than a blury pixel at any large distance. There's no reason to be surprised when you're only at the and blurry pixel stage that you haven't been able to comb the entire universe for intelligent life.

The one major problem with this question in general is that initially we assumed unbelievable high amount of planets could be habitable that probably aren't because they're just too close to the center of galaxies. That has lead us constantly assumed with zero proof that we should be seeing all this life even in our own galaxy.

I will take the opposite approach and say that intelligent life is so rare your lucky to have more than one intelligent species per galaxy and beyond that communication between distant galaxies is harder than we think. Prove me wrong!

I will also interpret the age of the Earth at about 4.5 billion versus the universe at 13 billion to suggest that there's only been a relative short amount of time for development when you consider it took 4.5 billion years for the biosphere to form and give intelligent life a chnace of happening.

Its too Easy to look at just humans development of intelligence and theorize that it could happen quickly, but there's no actual proof of that and really there's only proof that it takes about 4.5 billion years.

We may very well be some of the first .. to survive to this level of development in the visable universe for all we know at this point.... Once you solve all those questions then you can worry about the implications of artificial intelligence!