Struggling with cultural differences at a new job.

This sounds great to me. I don’t like or want casual chatter, and I don’t want to be friends with my colleagues. To the extent that the team I manage engages in this sort of thing, I just ignore it (they can do it if they want, but most don’t). In Slack, I have all the useless “chatter channels” on permanent mute.

I don’t work to make friends, don’t want work friends, and simply do not have time for MBA-type chitchat.

For my minimal social needs, I have plenty of friends outside work. As a commenter pointed out any work “friend” would toss you away like garbage if it was between paying their mortgage and you. It’s always wise to remember that.