There have been enough cases, where a producer sampled an original and pasted it more or less unprocessed in a project. IMO this is stealing ideas and hard work of others.
Many of us like particular artists and listen to their music often enough to have tunes, chord progressions, and rythms of successful songs in the back of our minds. IMO we should be aware of this and ackowledge that we might have just “copied” a too large part of the artists work into our own. What “too large” means has to be defined by some law or agreement. But there is always the option, to aks for permission.
I think many agree that some chord-progression should never belong to a person or organisation, but if a song has a particular style or making, which makes it stand out from others, then protection is justified … at least for a certain time. Even technical patents don’t last for ever. After some decades it becomes common knowledge and protection is withdrawn. IMO the same should go for music.
But let’s consider an example of a hard to miss phrase like the synth-progression of Van Halens “Jump”. It’s one of the most simplest patches on a poly-synth and not at all complicated to play. But it became something like the begin of hymn, which is recognised and loved by many people. Such things need to be protected … beeing simple or complex, be it the “match”, or the “zipper”, or something like a new “software algorithm”.
Of course that can happen. But it might be a very rare case in these days. With releases through internet platforms it should be at least possible to document that somebody releases a second title such that the time between the two releases is too short - judged by common sense - to copy the idea and run a full production. But if a title is online for some days or weeks, a coincidence becomes more and more unlikly.
Hope you all can learn something.