BuddyPress.org

@eric1704, you can check https://wordpress.org/plugins/social-articles/
If you are using any form plugin like WP forms, Formidable Form, or Gravity Form they allow frontend posting with their addon plugins.

@eric1704 yes, you can also use https://wordpress.org/plugins/buddypress-followers/

@eric1704 members can post activity and other members can also reply to those activities as comments which will be displayed a threaded conversation.

@eric1704 You can try free BuddyX theme