On a few of these ships strange markings were found etched into the metal hulls - anything else would've degraded by now. These markings, presumably writing of some sort, have been wildly different on every ship. Only 1 thing remains constant, a single symbol with only minor variations.

This symbol appears to be that of a star.

Humanity doesn't know what to make of this at first, we already know that stars existed long before these vanished civilizations did. Perhaps they were longing for stars, after so long in the intergalactic void. Or perhaps there's something we don't yet know. We are eager for answers.