I'm surprised at how few people have read "Candide" by Voltaire. It came to the same conclusion and was written when the US were still the colonies. I'm sure there were earlier works that would have said much the same thing, but it was so playful in its takedown of organized religion that the jokes still land centuries later.

Philosophizing and trying to figure things out is "keeping busy." Philosophy, when coupled with writing and teaching, is a very active pursuit. It has nothing to do with depression and depends on soberness of the mind and cultivation of perception.

honestly, this sounds like something a depressed person would say. Get some sleep, exercise, outside time, good food, and social contact. It really helps.