There are many things you can do once you've completed the puzzles! You can try to get all 50 elders, find all the collections, etc. VV2 doesn't reveal who the people that left are. You're right, though, that it seems that someone or someTHING is wreaking havoc on our tribes.... at least sometimes.
And Welcome to the forums!!! (For a really big welcome, you should make yourself an intro!)