Are talented creative musicians channeling their higher selves to bring in talents from prior lifetimes, or perhaps other beings like angelics, former performers now in the light, etc.?

This is not true in each and every case, it is highly variable, and even for those who occasionally have a higher being on board, it will not always be the case as it is rarely an all-or-nothing phenomenon in terms of someone's ability to make a credible musical performance. Those who are professionals have put in the practice time it takes to build their musical muscle, so to speak, but it can make a big difference nonetheless in turning an ordinary performance that is acceptable into one of greatness.