What if WE are the ancients that SF writers write about... that foundational race of sentients that (will) establish stargates and then sod off to who knows where...
It's just as likely it is us as anyone else.
That glorious, brilliant (skrreeech!!! WHATTHEHELL?). Well, us.
Think about that for a minute, and don't forget to write something profound in EBCDIC.
/johnny
A book I read about 10 years ago postulates that the dinosaur/reptilian overlords live under the earth and bred us as a slave race to do mining and other tasks for them or some such.