Yeah every musician has a story of writing a new song, bringing it to the band, and they say "oh, this sounds just like [song]." It's almost impossible to make something truly novel.
But beyond the originality !== novelty discussion, I'm not sure how we've come to equate 'creativity' (and the rights to retaining it) to a sort of fingerprint encoding one's work. As if a band, artist or creator should stick to a certain brand once invented, and we can sufficiently capture that brand in dense legalese or increasingly, stylistic prompts.
How many of today's artists just 'riffing' off existing motifs will remain, if the end result of their creative endeavours will be absorbed into generative tools in some manner? What's the incentive for indies to distribute digitally, beyond the guarantee their works will provide the (auditory) fingerprints for the next content generation system?
I have written and performed many songs over many bands. At no point did anybody compare my work to any other artist's work, because it is genuinely unique.