Where are you, fellow enthusiasts?

Out of the hypotheses presented, the fourth one seems the most realistic to me. However, I have vague doubts that humans will turn out to be those very Ancients, Precursors, First Ones, Creators, and other pompous names for the first cosmic race, about which crowds of younger races speak with bated breath. And they will find some Ancient and Great Artifact, containing the Sacred Knowledge of the First Race, and it will turn out to be 100 gigabytes of video with funny cats.