I listen to a variety of religious music: Catholic hymns, negro spirituals, southern gospel, etc. It is my understanding that the songs in the BB songbook are not the only “approved” songs that Catholics should sing. Am I understanding correctly?
You are correct. I assume by BB you are referring the Breaking Bread, which is one of many hymnals that can be used in the United States.
As long as all copy right laws are being followed there are many options that can be legitimately chosen.