There was an obscure reference once in the awake, 60s,70s, that said that "We are not mandated yet to colonize other worlds" so rather alien life already there it was the private opinion of that writer (it looked like he snug that tidbit in) , rather than extraterrestrials already being there, we would go there to make it so. perhaps by an extra-terrest-trial resurrection.
How many stars, planets have already died, whose light has not arrived yet?