I agree it can be a coping mechanism and a cultural thing. Many jews, for example, make jokes about the most serious of things. Many people in Asia, North Africa, Latin America and Eastern Europe (as venusss said) do it. Many Catholics and Muslims.

Maybe it's a somewhat typical Protestant thing not to do it, though it's also something seen in the UK (but arguably different). In Germany they even do it, though much of the rest of the world doesn't understand it or see it as humour, really not funny. Maybe for the Germans it's a bit compensatory, not a natural thing.

Maybe the US and some parts of Europe, maybe the Far East, are somewhat of an exception.

I think it's rather healthy. Taking things too seriously can be very dangerous. Better to overdo it, probably.

Edit:
Personally, I don't like much of the American humour, being a bit like that of the Germans, but funnier: very much only at the expense of others, cheap, without much self-reflection. Not always.

Another edit:
There are great exceptions: George Carlin, for example.