I don't have any experience building an open-source community, but I do have a lot of experience in marketing. With that context, here's some thoughts – hopefully they're helpful, if they're not, I guess you can just ignore them.

1. Link everything together. If I'm on your github it should be obvious how I can get to your discord/slack/website/forum and vice versa, don't make me work for it.

2. Build a regular rhythm to your comms/emails etc. If people opt-in to hearing from you, you need to hold up your end of the deal and commit to regular, quality updates. This will become the heartbeat of the community.

3. Pick 1 or 2 'brand' assets. Try to make them distinct, and then use them consistently everywhere. Your logo is probably a good one, but some kind of color combination/sound/flair should be distinctively you. Use these assets everywhere so that it becomes a visual shortcut in people's brains.

Ultimately, keep it simple, and just start. Don't overthink everything, you can always pivot and change as you move forward.