Asking this to the general audience because that's a comment I've seen quite a lot recently.
So, let's start with a list of communities that could be interesting to a wide audience, sorted by monthly active users (MAU), the most active being on top.
Those numbers may seem low, but remember that those are active users, who at least commented or posted in the last month. So even if you are afraid to be shouting to the abyss, there will be other people next to you to keep the ball rolling.
Also, please note that those communities are suffering from the current tedious discoverability of new content on Lemmy. I'm hoping to make them more popular with this post, as I'm sure those are topics that can interest a lot of people.
Another thing to keep in mind is that Lemmy cannot replace 18 years of content creation overnight. It will take time for those communities to grow to the same level of content and activity than there counterpart, but with a bit of time, we'll get there.
In addition, there are a few places to look out for new communities.
The first place to look for is https://lemmyverse.net, but Lemmy.world communities are currently excluded for some reason (https://github.com/tgxn/lemmy-explorer/issues/139).
A second place is this community: [email protected]. People tend to promote their communities there, you can also ask for a community you are looking for.
Finally, [email protected] provides a daily report of communities becoming popular.
Indeed