That's good info, but I don't think we have any misinformation being shared in this thread because OP asked about 'this forum', and also specifically mentioned "bitcointalk forum" when asking who was the first person to join it, and everything shared in this thread is regarding this forum.
Please check the bolded parts for reference:
I joined this forum a few months ago. After entering the forum, I tried to know the situation here. I don't know much about forums. I see people from different countries here. And they have good knowledge about BitcoinTalk. Now my question is, who was the first person to join bitcointalk forum? And how did he know about this forum?