You could be copying Halo, or Mass Effect (the Protheans), or 2001: A Space Odyssey (whoever built those monoliths), or the Cthulhu mythos (the Elder Gods), or Halo again (they do it twice with the Precursors!) the Legend of Zelda (the three goddesses), Metroid (the Chozo), the Hitchhikers Guide to the Galaxy (the Magratheans). You could be pretty much ripping off any sci-fi work with a heavy backstory. It's a common trope in science fiction tales, so you should be okay.
Wait, you're writing a book?! Nice, bro! Good luck!