The absence of such detections is yet another unsettling input to the Fermi paradox.
Of course there are 80,000 other explanations that are also fascinating. A wonderful subject.
Also most probably there isnt any way to travel back in time, since we would most probably be eliminated at the seed to not compete for resources or avoid aggression. For all wonderful things mankind did and does, we are still deeply flawed and highly emotional primitive beings, and we may kill ourselves due to this.
Add to that that we probably aren't as "normal" as we initially believed. A solar system with small rocky planets on the inside and big gas giants on the outside seems to be the exception and was very important for earth's development. Then there's the above mentioned "void" we are in, and probably other things we don't realize yet.
There's a really good case that we are among the earliest spacefaring civilizations
Is this actually the case?
Emphasis on "observation".
Currently we infer planets that orbit stars that are extremely distant by starlight dipping in intensity .. this is a method that works better with larger planets and that skews the results of observing distant planets.
We have observed some small rocky earth like planets IIRC but these are rare, observations perhaps due more to luck in looking than frequency of existence.
This is the crux of the problem; does the distribution of planets we observe match the distribution of planets that exist?
A "reset button" would be more like the impact that created the moon: ramming a Mars-sized body into Earth turns Earth into a magma ocean. Nothing survives that. By comparison, the KT boundary asteroid is small potatoes.
What would be horribly unsettling is detection of ET intelligence, as it would imply either interstellar travel is impossibly difficult or that the Great Filter is in our future.
Which describes our species' travels until only a few thousand years ago.
Without travel beyond our solar system, we won't last forever.
And that's kind of sad for me.
For one thing, a large fraction of possibilities involves simulations. In a simulation with successful traits, some constants and elementary particles might turn out to have been misunderstood later on...
IIRC, a warp bubble a few km in diameter moving at <0.3c produces gravitational waves at a frequency just beyond what we can currently detect. Superluminal warp bubbles haven't been simulated, apparently that's beyond the computational resources available to this team.
Don't expect a real detection any time soon. We'll need another generation or two of development on our detectors and to actually simulate a more realistic (small and superluminal) warp field.
Personally, I think we'll find something once we build detectors good enough. I'm a firm believer that purely based on statistics there has to be someone else out there. I also choose to believe that superluminal travel is possible because the universe would be a much less interesting place otherwise.