Nobody wants to tell you what you can and can’t use. Including me.
It’s a mine field.
There are too many moving parts.
We have copyright services. But they don’t actually provide you with any guarantees that what you are using is covered by them.
There is no “one licence to rule them all”
It means that you have to plan ahead to use another person’s material.
The death of the hymnal
What is a good approach?
What are the things that can be covered by copyright? Words, music, arrangements of music, typography, performance, adaptations, inspirations. And other things only limited by the imaginations of lawyers and marketers. And they have very good imaginations.
The threat, intimidation and obfuscation are genuine disincentives to using anything
It’s an industry of its own, independant of those who create content. Businesses exist to give “coverage” to those who want to use an artists work.
A content creator wants their art and artifice to be appreciated. They want the costs of their creationb covered. They want to draw an income to profit from their labour.