The more people who help create an artefact, the more people are likely to share it.
The more it’s shared, the more people are likely to join and help build the next artefact.
Communities aren’t never-ending streams of discussions. They are places to use the collective knowledge, passion, and resources of members to build things that help every member.
Each artefact increases the value of the group and attracts more people.
An artefact can be anything you like (books, videos, products, prototypes, events etc…). The only requirement is it involves as many members as possible and it lives on the website indefinitely.
You probably don’t need more activity than you do now, you need to be working on more artefacts. Don’t create them for the community, create them with the community. Speak to a few members, define a problem, and then begin soliciting solutions for the problems.
Go forward from there.