What to write a song about?

Whenever I’m stuck in a rut and don’t know what to write about, or whether I should write a song about something, I remember what Nick Cave wrote in his Red Hand Files. He was responding to the controversy about ChatGPT, but his words define what it is to be an artist, and what it means to write a song. Particularly this:

What makes a great song great is not its close resemblance to a recognizable work. Writing a good song is not mimicry, or replication, or pastiche, it is the opposite. It is an act of self-murder that destroys all one has strived to produce in the past.
It is those dangerous, heart-stopping departures that catapult the artist beyond the limits of what he or she recognises as their known self.