In a universe where intelligent life is common throughout the galaxy, there'd be no way to tell what our species would have become left to its own devices. What discoveries we would have made, what cultures we would have created, what our destiny might have been.
The only way to discover it would be to simulate human life on a planetary scale in a universe where other intelligent life is mysteriously absent. Which is exactly the situation we find ourselves in.
Even if we continue to survive as a technological species for another 1000-5000 years and not push ourselves to extinction even if we go 10,000 years it's still a spec on the timeline of our galaxy not to mention our universe.
It's very likely that life is very common, technological species might also be common but this is on universal time scales it's also pretty likely that because species and entire planets go extinct all the time that the they simply do not overlap on universal time scales.
- in a simulation, and they didn't bother to simulate other parts of the universe in high fidelity.
- in a zoo, and somehow we're blocked from seeing other civilizations.
I don't buy, for an instant, that in a universe of this size, we'd be the only life forms.