The Sage of Sagittarius

There are 300 billion stars in the Milky Way Galaxy and many ought to have life. Why haven't we been contacted?
All life on Earth derives from a common ancestor, the LUCA, the Last Universal Common Ancestor. What if a singular seed of life spread throughout the galaxy? What if the life that springs from that seed has a nemesis?
Zila Aropova Biddey is a multicultural girl who wants to be a diplomat. She finds her love, Manny, a genetic engineer, and a mentor, the Great Sage. The Sage gives her enhanced memory and perspective, assigns her a crew and an FTL vessel. Her assignment: Find the LUCA. Traveling from planet to planet, she searches out life and tests it against the LUCA premise.
The nemesis is untouchable and multidimensional. This adversary may be as old as the universe itself and is now focused on destroying all life on Earth. Zila is suddenly thrust into the middle of the most important conflict in the history of life itself.
What can young Zila do against such odds? At the very end, are love, cleverness and other human traits enough?