Those aren't necessarily mutually exclusive options. Something can be "open source" and still have only one contributor.
Art has been quite open source in its workings since centuries. Look at how artists were joining masters to learn the art and how they "forked" masters' techniques to create theirs. Personal vision is not precluded from open source, to the contrary it is encouraged.
R&B, EDM, pop and so on wouldnt have much left without remixes and sampling.
But in that case money changes hands. That's pretty different from open source.
Nothing about open source precludes money from changing hands. Case in point: Red Hat.
Yes. Open source is about way more than the finished product; it's about the shared community, techniques, processes, and tools.