To add to the other comments, it's related to a Da Vinci-esque character - a genius inventor with the creativity to come up with the ideas, but not always the capability or technology to see those ideas come to life (then coupled with your own invention experience and knowledge to make workable pieces of technology).
It also plays on things like Damascus steel, which was far superior to other steels of its time, but which we even now do not fully understand exactly how it was created (even though people have sort of replicated it, and developed far superior steels).
It explores the concept of lost knowledge. Also in the mix is how war fuels innovation.
So, I understand how on the surface it could seem odd, but it's well considered and makes sense in context.
Edit: Oh, and yes, the concept of technologically advanced precursor civilisations is rife throughout fantasy and science-fiction - Mass Effect's protheans, Halo's forerunners, Assassins Creed's first civilisation, Stargate's Atlanteans, etc. Note, however, that this inventor is just one part of one dig site, and this trope is not core to our skill. :)