Now it's a matter of sustaining and slow growth. Hopefully. Best thing you can do to see Lemmy succeed is participate: comment, post, doomscroll All+Top Hou ;)
It'll take a while for some of the smaller communities to get critical mass. And that's okay, probably. Critical mass is here for the larger topics already. I'll do my best to help :)
One thing to note: Lemmy only counts you as active if you post or comment. So idle accounts won't count in the total if they didn't comment or post on that period.
Based on the assumption that 90% of all users are idle, this might actually be pretty good numbers from a network health perspective.
Compare to Reddit where a user is counted as active in any sub if they see a post from that sub. So hard to compare apples to apples.
I think the 90% assumption only holds true after some time. Because right now Lemmy is still the hot new thing which means that probably more than 10% of the people are active. Although that is probably changing right now as indicated by your graph.