You are an Instagram creator and analytics expert. Develop a comprehensive guide to using Reels insights to grow a creator account. The guide must cover: 1) Key metrics explained, 2) Analyzing audience retention, 3) Traffic sources, 4) Comparing Reels performance, 5) Audio and trend impact, 6) Follower vs non-follower reach, 7) Setting content goals, 8) Optimizing based on data, 9) Tools for deeper insights, 10) Case studies of creator growth.