Moribonds translates to "dying" or "moribund." It's a strong, somewhat formal word that isn't commonly found in everyday song lyrics, making it particularly striking.
In the context of Benjamin Biolay's song, which paints a bleak picture of a decaying society, "moribonds" is used to describe the state of political ideologies: "Il n'y a plus de gauche, il n'y a que des moribonds" (There's no more left, there are only the dying). This word powerfully conveys a sense of decline and hopelessness, reflecting the song's overall melancholic and critical tone.
Benjamin Biolay's "Sans Viser Personne" is a pretty blunt and darkly humorous take on disillusionment. The title itself means "without aiming at anyone," but the lyrics feel like he's aiming at just about everything! He starts by saying there's "no love, only illusions" ("Il n'y a pas d'amour, il n'y a que des illusions") and that we're left with "only long sobs" ("il n'y a que des sanglots longs") instead of tears. It's a pretty bleak outlook on the world, suggesting a loss of connection and harmony, with lines like "no more osmosis, no one in tune" ("Il n'y a plus d'osmose, plus personne au diapason").
He continues this theme of decline, seeing only "concrete slabs" ("des dalles de béton") and a world where things have gotten worse. He's "disappointed in you, disappointed in us" ("Déçu de vous, déçu de nous"), and declares he no longer believes in anything at all ("Je ne crois plus en rien du tout"). He even laments the loss of "summer" and "beautiful seasons" ("plus d'été, il n'y a plus de belles saisons"). It's a cynical, almost sarcastic look at a world he feels has lost its way, leaving behind only divisions and bad decisions.