not familiar enough with libby or the narrators, but here are some fun non-fiction books that aren’t biographies, pop psychology, or self-help, but which might have general appeal:

• almost anything by Bill Bryson, e.g. At Home, A Walk in the Woods, A Short History of Nearly Everything
• 1491 and 1493 by Charles C. Mann, which debunks a lot of the common myths about Columbus, indigenous Americans, and American colonialism