Here's the scenario: living deep underground, far from any influence of modern humans, is a civilization of what can essentially be considered early Sumerians (from 3000 BC). Disregard how they got there, why or how they've stayed there, how they haven't been detected, and how their technology and knowledge have remained locked in the Mesopotamian era. If it makes it easier, assume they have been kept in stasis since 3000 BC.
All modern humans evacuate Earth, taking with them everything which can be moved, and disassembling the rest. This means they leave things like large buildings, massive factories, and the like. All machinery and others parts have been removed, leaving only skeletons of buildings left.
With only these artifacts present, what advances would the Sumerian civilization immediately gain?
Assuming that the Sumerians emerge from their underground lairs once we have evacuated, will they be merely bewildered by what they see, or will they begin to understand the purpose behind at least some of it? If so, what?
NOTE: I'm talking about advancements here. That is, what will the Sumerians be able to understand and duplicate? For example, if they see a steam engine (which they won't because it's gone, but as an example), would they be able to eventually figure it out much sooner than they would on their own? What about building structures? Would they go from caves or simple huts to mock-skyscrapers? What advancements would they gain?
- The modern humans have evacuated Earth to avoid being wiped out by a comet collision. Assume that they left tomorrow. They will not return. Don't worry about the technology required to pull off such an evacuation. If it makes it easier, assume benevolent aliens evacuated them. They have taken everything they will ever need, including:
- All technology and electronics. 'Technology' here means anything we've ever made and can move. So ancient steam engines and home tools go, but things like the skeleton of the Arecibo Observatory remain (stripped of devices of course; primarily just the radar dish).
- Many permanent fixtures (like telephone wires) have been disassembled for transport/resources
- Most homes have been disassembled for resources. Large skyscrapers and other massive buildings have been stripped of anything valuable and left.
- Farm fields have been harvested, and then left unattended.
- Power plants have been disassembled for parts and resources, leaving only the outer walls behind.
- All books have been taken. There are however more permanent writings, such as carvings, sculptures, and drawings on walls.
- Graveyards have been mostly emptied, but many tombstones remain untouched.
- Things like roads, subway tunnels, and massive bridges have been left, stripped of machinery. Things like railroad tracks and small bridges have been salvaged for resources and removed.
- Archaeological dig-sites are intact, but everything modern has been removed from them. Just the excavation itself remains.
This question is not a duplicate of this question. That question is similar, but deals with what humans would find given a gap of 3-5 million years. My question asks what early humans would find and how it would effect them, if we left today, taking nearly everything with us, and they emerged shortly afterwards (a matter of months).
If more details of what is left are required, let me know and I will happily provide them.