If they were as advanced as we are now, we would have seen that the atmospheric CO2 levels had been higher back then, no? This paper draws the conclusions that such a civilization would be visible in the geological record.
I think we forget how many more people there are now compared to just 100 years ago. At -5000, there is an estimated 5M people. There's more than 1000x more people now. Per capita carbon footprint would be quite wild to leave any kind of mark on the planet with a total human population that is smaller than a single modern day mid sized city.
(Data is from worldometers.info/world-population)
Another is the plants and animals they used for food. Why are some plants and animals still indigenous to certain areas, assuming there was a small globe spanning civilization at some point in the last million or so years? Shouldn't this civilization have at least brought the crops and livestock to other areas of the globe they visited?
I can imagine a world where electricity and batteries were developed before the mass exploitation of fossil fuels as, afaik, there's no specific technological requirement on one for the other to exist.
Well of course the start of it predated the mass adoption of steam engines, but as I understand it the start is generally considered to be when steam engines were first put to use pumping water out of coal mines, that water then being used to flood canals to transport the coal. That synergy was incredibly powerful, making cheap coal available in cities which allowed urban populations to rapidly grow, providing a workforce for the factories which would eventually (not initially) also be coal powered. That's the industrial revolution as I learned it.
> Terra preta soils are found mainly in the Brazilian Amazon, where Sombroek et al. estimate that they cover at least 0.1–0.3%, or 6,300 to 18,900 square kilometres (2,400 to 7,300 sq mi) of low forested Amazonia; but others estimate this surface at 10.0% or more (twice the area of Great Britain).
Primitive people were not stupid, they just needed a lot of time to figure out things that we now think are obvious.