Its been ages for me, so I may be incorrect now. I think the chat is not persistent and I am pretty sure there is no channels. Its most definitely not set up how discord is where its more of a chat client that has voice rather than a voice client that has chat.

man I wish mumble had a better interface and a chat function, it could real FOSS competition with Discord, but the lack of a chat feature is holding it back

Think of your instance you signed up as as your email provider. Using that email you can send messages to anyone else who has an email. You do not have to pick a specific email provider to use email, gmail, hotmail etc they can all talk to each other. Lemmy works in a similar way except it not limited to DMs, the instance you sign up for allows you to talk to people across all Lemmy instances and see posts from other instances. When you go to “All” on Lemmy you are seeing all posts across all instances. When you go to Local, you are only seeing your home instance.

Been checking and commenting on Lemmy everyday since I made my account. Its my new first opened app of the day now