There's a lot to think about when it comes to new player retention: quality of guides and wiki pages, new player turnover rate, server activity, etc. There is however one key facet of new player retention I see many communities completely ignore: community atmosphere.

What do I mean by community atmosphere? It's how the community members speak to each other, their frequent topics of conversation, the ways in which they discuss their game, overall server positivity, and ultimately what the moderators do to protect the atmosphere.

Birds of a feather flock together. If your Discord server is an unmoderated cesspool of excessive toxic shitposting and bigotry, you'll attract people who want to be a part of that and push away most of anyone else.

Even when not taken to the extreme, communities who frequently post throwaway negative opinions about the game as a meme create an atmosphere of negativity.
"Game's shit anyway."
"At least it's not (game name)."

Long form well thought out criticism is NOT toxic or negative.

If you want to attract new players and retain new players, your server needs to take the game you play seriously, have a positive, welcoming atmosphere, and be led by an active moderation team who cares.

If your community is focused on off topic, shitposting, memes and shitting on the game you want people to play, then your community will only attract people who ultimately don't care about playing your community's game.

The atmosphere of your community is the first thing new players will judge, and first impressions mean everything.