There's got to be one species that's impressed by storytelling even if it's not solely humanity's "thing" in amalgam -- Gallifreya
One good thing you can plausibly state about humans is that time spent with them is never boring. Of course, that was their chief combination of blessing and curse. They were never boring.
Most species took to space for reasons of economy. Things on their homeworld were no longer easy to obtain. Yet there were metals in abundance out in space. Few at all went to see what was there.
And rarest of all were the ones who went because of stories. And not just the stories told by those who stopped by accident on their planets. No. The stories they made up themselves about what might be out there. The stories that held mirrors up to themselves. The stories that gave themselves hope for a better future. Or the stories that made them laugh when they thought all hope of laughter was lost.
They came in space ships. They came in the cargo-holds or the spare berths of vessels headed for the next port. They learned Galstand and picked up trinkets. And they told stories. Of ancient deeds of valour, of brave souls surmounting all the odds. Of dumb luck and favour from the gods. Of clever minds examining all the clues. Of love, loss, betrayal, and victory.
Galactic Society was in awe. They could invent new stories at the spur of the moment. They could take in old tales and twist them about. They collected culture and they passed it on. Some sang. Some rhymed. Some just told interesting stories about fantastic places, of beasts, of treasure, and of heroes.
Humans weren't allowed to set foot in Galactic Alliance space. Not properly. Never officially. They remained on the outskirts, in the places too far away to enforce and too lawless to bother. But wherever four Spacers clustered around to swap tales over something fermented and slightly toxic, there was one of the Humans. Spilling words out of their mouths and turning air into Hours.
It took the Galactics quite a few years to learn that the phrase 'silver tongue' was a metaphor. It took some species quite a long time to learn about metaphors. And by the time they did, humans were among the first Deathworlders to join the Galactic Alliance.
And restaurants who knew their business always kept a comfortable chair in the corner with the best acoustics. And let the storytellers run up a tab.