Let us make a few assumptions first, and maybe throw in some facts as well.
1. What are the odds that there exist or has existed life beyond earth?
Well, even if the chance of a given solar system or any of its planets has life, we are talking about an infitesimal number of galaxies with their solar systems and planets So I'd say the odds are pretty good, almost so good that I would not bet a penny against it for a dollar.
2. What are the odds that evidence of such life or remnants of such life could be found within a few decades in human time scale? Almost impossible, if not flat out impossible.
Why do I say that?
Well, I learnt when I was a kid watching a Sagan program that the universe was sort of like a giant dough with raisins i it, that is ever expanding. The odds that one raisin will ever meet another raisin is pretty slim , and the raisins will get further and further apart over time. So whatever crap they find digging in mars rocks is likely stuff from our solar system, and if they find any stuff from outside the solar system, due to the nature of the big bang, you would only find stuff from the very birth of the universe.
Since it takes up to a few billions of years to get all the conditions right for the nurture of life, I'd think it very unlikely that any such primordial space debris would have any remaining evidence of life.
Aliens here, what utter nonsense. Assume that time travel and travel beyond velocity of light is impossible. Given the distances at play, an alien could not target earth, or even our solar system for a trip. What they observed from our solar system would have been millions of years old when they saw it, and given the expanding nature of the universe, they might even need to break the laws of physics to travel in that direction fast enough for millions of years to catch earth.
If life was achieved in the very few birthing moments of the universe, and if intelligent species managed to come up with space travel and colonized a fair amount of of the primordial matter, we still would have only infinitesimally small chances of ever finding any evidence of this.
I find it distasteful that NASA, which should be founded on science is engaging is such claptrap gallopping charlatanism. The universe is plenty interesting enough as it is, no need to add hobgoblins and other hocus pocus.