Interaction through a medium is social media i guess. But i wouldn't call ist that. Lemmy, WhatsApp and YouTube aren't really social media for me. I don't throw personal stuff into the void of people i more or less don't know in hope to get likes.
I would argue that a forum is a type of social media. It's very different in that it's as anonymous as you want it to be. But it is still a place where people visit for the purpose of socializing
Where I live, Facebook is used by baby boomers, so yes it's still used. But that's the cliche. When I log in, I still see some millennials being at least online and some even posting unironically. But it's mainly dead for millennials
Can't say for OP but it still very much is where I live. People use groups for all sorts of things (neighborhood chats, classes, hobbies) and Messenger is the go-to way to contact everyone (which I admit has one advantage over all other mainstream means of contact, which is not requiring to share one's phone number, only name)