1. That most people (including me) are utterly clueless a lot of the time, including people in very high positions of authority. Don't sweat figuring out the big questions or trying to solve problems that have been a feature of humanity for all of time.
1a. This is kind of a side point ... expertise in one thing doesn't make a person any good at other, unrelated fields. When I was younger, I used to think programmers (like me!) could solve the world's problems because "we're so smart and logical". I soon realised being a decent programmer just means I'm a decent programmer. Accepting this made me a lot more "chill".
2. Cynicism is probably justified – mankind has done A LOT of screwed up things – but ultimately unhelpful if you want to live a happy life. For those who've seen Everything, Everywhere, All At Once, the Ke Huy Quan character epitomises I think the best way one can live life – embrace the absurd, be happy with what you have, love your loved ones, be a bit silly and don't take everything too seriously.