So to burst your bubble, if a future civilization happens, nothing we have done is going to be detected and they will be just as blindly bumbling as we are.
I agree with you on the blind and bumbling part. But as for whether or not a future civilization could detect our past presence on this planet and elsewhere in the solar-system, that really depends on
when that next intelligent species developed their own technological society capable of performing archeology. As it stands, if humanity was wiped by some superbug or nuclear apocalypse sometime in the 21st century, there are a host of species that could take on the mantle of Earth's dominant intelligent species in the next millions of years, after the proverbial dust settled and the ecosystem normalized. I think I need not reference which species, since all of us here probably can make some educated guesses. If nature fosters intelligence in a species like it did with us, 10 million years would be enough time for a hypothetical species of advanced crow, or even some other great ape (
for example) to evolve to human-level intelligence and society - if natural selection takes that route. In that time period, there would still be some evidence of our presence on this planet that could not be conveniently explained away as natural by corvid or chimp scholars.
Of course our buildings for the most part would have eroded away into dust, but far underground governmental bunkers, nuclear waste dumps (the structures themselves, not the materials stored therein since most have half-lives of ~few hundred thousand years) and old mines may still survive geological changes. Certain surface features might also survive the test of time - the pyramids of Giza (or their dispersed ruins) might still be present for up to 50 million years, barring any serious continental shifts or natural disasters. Likewise, some other monuments would last an incredibly long time. There would also be a curious absence of oil, heavy elements or rare Earth metals in places where geologists would suspect an abundance. And we have not even mentioned the possibilities of future archeologists finding the fossilized remains of
homo sapiens sapiens and certain hardy technologies in geologically static conditions conducive to fossilization. I imagine a mass grave site resultant from a superbug outbreak, if situated in the right spot, could be a treasuretrove for future non-human scientists to study.
If humanity wiped itself out some time in the future, and we managed to find a foothold in the solar-system, then space debris and evidence of exploration
could possibly last an incredibly long time in the cold reaches of interplanetary space or on barren, airless worlds - if protected from micrometeorite impacts. In the future, we might also manufacture exotic materials that may withstand the test of time far better then concrete or steel. So the longer we exist before going extinct, the better the chances are that someone could detect our presence in the future.
Also as far as we can tell, it took the last 3.5bil years of evolution to evolve us,
We cannot say for sure that we are the first. There may have been a number of intelligent species that could have achieved some semblance of society before going extinct. It is bold to claim otherwise, since our knowledge of the fossil record is patchy. 3.5 billion years is a long time (realistically, intelligence on land could have evolved starting at ~300 million years ago when life was really diversifying on land - it is doubtful that it could evolved any earlier). On those timescales, NO evidence of intelligence in the fossil record would survive aside from the barest traces of fossilized detritus - but only if they did not live in an environment very conducive to fossilization processes.
It is an interesting statement to make - saying we are the first on this planet simply because we have not yet discovered intelligence in the past, and yet also state that future intelligent species would never be able to find evidence of us despite looking. Perhaps these future archaeologists
could misinterpret the evidence of our presence, but eventually the idea would be broached that another intelligent species lived on their planet, in order to explain certain anomalies (on Earth or in space). But the question of time still remains regarding our detectability for future beings. I would not take the absence of clear evidence for intelligence in our past as evidence that we are the first on this planet. We ourselves might be guilty of misinterpreting some geologic anomaly that was in fact caused by intelligent activities. An example that comes to mind is that of the Ordovician-Silurian extinction event (although this is baseless speculation on my part).
These are my thoughts on the matter. I find it passe to disregard our mark on the geological timeline of Earth (however small it may be!) and also say that based on paleoscience so far, we are the first here on Earth. We may well be, but it is unscientific to disregard the possibility.
In the long term however, I completely agree that time will erode any trace of us, on Earth or elsewhere. It would be exceedingly arrogant of us to say otherwise.