It seems to me like music has a clear value for survival. Music is a type of cultural transmission (memory technique), and humans do sexually select for musical ability (ask a musician).[1] Groups that sexually selected for the ability to transmit oral knowledge through generations (via memorization, including things like meter, rhythms, melody, and rhyming) probably had a greater chance of survival. Before writing, people stored their cultures' encyclopedias in their minds, which often involved music in some way.[2] Cultures also organize around music, people follow the ideas of musicians, etc. Napoleon made some interesting comments about the active use of music in leadership and group behavior.[3] A prehistoric human with an ability to organize groups through music probably had a higher survival/reproduction rate in general, or at least benefited the group through organizational techniques.
[1] http://journals.sagepub.com/doi/abs/10.1177/0305735613482025
[2] https://www.allenandunwin.com/browse/books/general-books/pop...
[3] "Of all the fine arts, music is the one which has the most influence on the emotions, and it is this influence which the legislator must encourage most warmly. A piece of "moral" music, one by the hand of a master, cannot fail to touch the heart and has much more influence than a good, "moral" piece of writing, which moves the mind but has no effect on our behaviour."
Look at the "haka" of the Māori and tell me you wouldn't be scared facing that.
https://en.wikipedia.org/wiki/Sexual_selection