Why? All the metal we dug up apart from the tiny fractions in space and the ocean is literally lying around on the surface. Maybe encased in some concrete but it’s not really hidden.

In the event civilisation totally collapses all our current shit will just lay around. Getting all sorts of metals will be easy, aluminium? It’s just chilling in kitchens, steel? Yep, you don’t even need to make it from iron just melt it. Copper? Electrical wiring, millions of tonnes of it.

The only really difficult ones for them would be coal and oil.

You could rebuild a very technologically advanced society just mining shot we left around, sure if they wanted to get to the same level they’d need to dig deep for certain things but that’s way past the point we needed to this time around.

Also, all or technology is incredibly well documented, and in the event society started collapsing you can bet people would go out of their way to keep hold of some very useful things.