Except they have the high ground. They can drop rocks on us.

Also, being able to use technical devices doesn’t mean you understand them or know how to make them.

Maybe the civilization they were in before would be able to do all that, but they can’t now, doesn’t mean they don’t still have a few “super weapons” they can fall back on.

Or, like I said, just throw heavy objects at us. It’s easier to go from orbit to ground than from ground to orbit.