What if the universe is infinitely more complex than that? I certainly think it is.
There's a theory just on the fringe of mainstream science that says if the universe were infinite, that even if intelligent life was unique to Earth, eventually in an infinite universe all possibilities also become infinite. Meaning there would be an infinite number of Earths spanning the infinite reaches of space--alternate realities if you will. Extend that theory just a bit to allow for the possibility of other intelligent life, no matter how rare the case is, and in an infinite universe that seemingly rare case of other (extra-terrestrial) intelligent life becomes just as infinite as our own existence in our universe. That's not to say that each and every planet capable of supporting life in any form would necessarily be so. What ever the odds are--be it 1 in billions that life in any form exists elsewhere in our universe, or any other outrageously low chances--they all become infinite. The only difference would be the average distance or time-span in between each occurrence.
For the sake of argument let's imagine that the only life in the universe is terrestrial life. We could say that in every instance of Earth, things are exactly the same, but that would be a very boring universe. For all we know that could be all there is to it. I would rather imagine this is not the case, rather that each version of Earth, even the solar system and our own Milky Way, are each slightly varied. So again, even if each variation is a negligible amount, through infinity there would eventually exist places that are so utterly alien to us that it would be hard for any of us to label many of these worlds another Earth. Essentially we humans become the aliens. Or one could go so far as to say that on some of these other Earths humans died out and something else took their place as the dominant intelligent life, or that humans had never come to be at all.
If instantaneous space travel ever becomes possible for us (think worm-holes or other means of travel that would bend the fabric of space) we could end up discovering one or many of these other Earths. The thing that could really cook your noodle later is, what if the majority of the ones we then discover are so vastly different from our own tiny piece of the universe that we never realize we're in contact with our galactic cousins, humans from another distant part of the universe, from one of these other alternate Earths? Even if we stumbled upon another version of Earth that was only marginally different from our own, such that it was easily recognizable, it would only prove to us that my theory is partially correct. That is, the universe is infinite and because of that fact we are able to find other versions of our world with humans nearly identical to us living there, these alternate realities as I call them. Would it even be possible to prove that the drastically different alternate realities--the ones unrecognizable as other Earths--are really just different version of our own reality, assuming it was true? For that matter how would we ever prove that an alien race is not another version of us?
All possibilities become truth in an infinite universe. Every question could eventually be answered with "yes" and "no," simultaneously.
Is the universe infinite?