The source data shows that while active users are down, the number of posts and comments are near all-time highs. While you need new users to help counteract churn, I think the higher post/comments count points to what I think a lot of people feel here: that quality seems to keep getting better and better.
Regarding how to bring more people in, I personally like how different lemmy servers have slightly different characteristics but each seems to appeal to larger groups. I see a future where there’s probably a small-ish number of large servers that cover broad groups of people.
These comparisons feel like people trying to compare Michael Jordan and Babe Ruth and asking which was the better athlete.