Those are fair points, but consider that they just put the next civilization at the same level we were; we didn't have the technological know-how until we invented it, we didn't know how or why to use different ores until we worked it out, we didn't know where the ores were to be found until we gound them, and harvesting pre-refined material is much less intensive than that, and well, we've warred, and continued to war over access to resources.

Basically, we've dug up lots of the easily accessible ore, which has a low density (you need to dig up maybe 4 tonnes of rock to get a tonne of iron ore, and that is only between 50-75% iron, for instance) and buried it more shallowly, and at higher density. There's still work to do to extract it, but it's manageable with fairly low tech.

Energy sources are a little more complex, but we've bound up a lot of hydrocarbons in plastic and the like, which should be usable, if not ideal in their raw form.