A civilization that got to "industrial" but didn't make it to the nuclear and particularly space age certainly seems like it could leave little trace over long periods depending on how the cards fell. However, if nothing else our civilization has made a habit of disposing of geosync satellites past their life time into super synchronous graveyard orbits that will last a really long time. At the rate things are going there is also reasonable chance we'll have a much more significant presence on the moon at least before any complete implosion seems probable (if we get eaten by AI that doesn't spell the end of development so doesn't count by itself, the AI would then have to also implode or leave no trace for new biological life to arise). Any sort of lunar base would also likely stick around a very long time at this point with the heavy solar bombardment no longer taking place. Granted, a new civilization would have to itself get quite a ways along to notice these artifacts and what they were if everything on Earth was gone.
I've wondered about stuff we leave off planet too. Like the stuff we left on the Moon. Our rovers on Mars. The JWST. Seems not entirely crazy to be looking in those places for evidence of past Earth-borne civilization.
Yes. Everything in orbit above an extremely small size is tracked. Very important for navigation. And satellites themselves are lenty large enough to be visible with a relatively basic telescope so in that respect actually I was probably too conservative, early astronomers would see them although it would take longer to realize they were artificial, but still long, long before space age. And know there were artificial objects up there would probably change history late 1800s.
