And in the 50s, it was jazz motifs variations. And in 40s, eh, just take a quick stroll through Ink Spots repertoire [1] - it's basically the same song all the time. And few decades before that, it was just sheet music reproduction.

70s and (particulary) 80s were all about sound texture cloning. Were it particular guitar amp/pedal arrangement, or korg/roland sound du jour.

I don't think it changed much in essence, only in form of cloning flattery. Today, kids buy trap samples.

[1] https://www.youtube.com/watch?v=TmT8S3qZnNk&list=PL210003EC6...