Well as you mention the light speed has a limit and when you are observing the universe due to that limit you are observing just a very limited portion of it and also very old, since to “see” something we need light.

And we know is very old because when we watch the furthest possible away we are literally seeing the start of the universe happening right now

So, who knows if the universe is plagued of civilizations or AI, the reason we don’t see them is because we are seeing everything around us with a massive delay

Also the universe can be even bigger as we consider, after all we only can see the observable part of it which is regulated by the light speed. It could be perfectly be that is so much big that we are just a very small point on it that perhaps is just placed in a very empty and boring region

For last consider this: we live in the same world than many other biological species, so much in the same place than we often clash with them (we have them in in our homes in our gardens…). But even having them so much present, when is the last time you have considered an ant or a squirrel relevant at all for your life? Even having them so near? You didn’t, because intellectually they mean very little for you, that much that you don’t even think on them.

So if there are extremely advanced and intelligent species out there who are much more intelligent than we are compared to our ants and squirrels, with the gap of the exponential growing that Ai would have, we would be nothing else than more ants and more squirrels. For them and our ants and our squirrels