You are mountain biking. It is supposed to be fun. You’ll want to chat to the other riders – this is part of mountain biking. Acceptable places to stop and chat include; the top of a climb, a junction in the trail, a fireroad climb.
You may also encounter the occasional road cyclist (or ‘roadies’ as they are often termed) as you ride to and from the trail. Do smile and wave at them. Many will ignore you, but it’s only because they know you are having more than them on your mountain bike.