The Milky Way galaxy is “only” 100.000 light years across, so any planets we see around stars in our galaxy we would only see about at most 100.000 years in the past. So it would be very unlikely there would be detectable life now, where there wasn’t 100.000 years ago. And even if there were, it wouldn’t be complex life.
The most distant exoplanet we’ve found to date is 27.710 light years away, so we see that planet as it was 27.710 years ago. We’ve had humans running round for at least a 100.000 year on Earth, so if there are any aliens on that planet we would see them.
Almost forgot the mandatory XKCD reference: xkcd.com/1342/