Dolphins and most whales are predators, but yeah - there may be a social aspect to it as well for the primates. A good point. But what does it say about humans, who are both predator and primate?
Puritanism didn't mean anything when Plato and Aristotle were around, but I'm sure you didn't mean to ascribe them to that specific viewpoint. What you find, however, is that other cultures are just as serious - the Laughing Buddha you mention, Boddhisatrva Matreya, seems to be unique in all the world as a benevolent mythological figure who laughs. There are trickster gods everywhere, of course, and they always laugh - but tricksters aren't exactly benevolent. Joy and revelry, meanwhile, are themes as in the Abramic religions as anywhere else.
I don't know why you're trying to drag class warfare into it, though. Plato and Aristotle were aristocrats, but both were avowed proponents of meritocracy - Plato, in fact, was the first person in recorded history to suggest that the ruler of a nation should, as a matter of policy, be the wisest person. The Puritans who settled America were poor farmers, just peasants. Can you imagine a British aristocrat extolling the virtues of the famous "Puritan work ethic"?
And the assertion that wealthy classes disliked lowbrow entertainment is nothing short of (dare I say it?) laughable - in Europe at least as much as anywhere else, the wealthy were the patrons of the low arts as well as the high. Opera and theater had their origins as really coarse comedies and satires, and to be an actor was considered about as reputable as prostitution - but who do you think paid for them, if not the very same French and English and German noblemen who not only patronized their writers, but also watched the shows?
The idea that only the educated (hence wealthy) could appreciate the fine arts has been around as long as there has been fine art, but the inverse idea, that only the uneducated could appreciate lowbrow art is a relatively modern one. Did not, after all, Caesar watch the gladiatorial games along with the masses? Were not Shakespeare's comedies (and they were lowbrow back then) patronized by the Queen and the commoners alike?
Classes existed before Marx, obviously, and aristocrats have distinguished themselves from commoners since as long as aristocrats have existed. However, the idea of class warfare can really only be traced as far back as the French Revolution. Prior to that it might be more accurate to call it class politics or class economics.
The fact of the matter is that Christianity spread during the Middle Ages, during which time Christian thought was dominated by St. Augustine and Thomas Aquinas, who were convinced that mankind was depraved and fundamentally evil. Its roots were also drew deeply on the ascetic tradition, where denying oneself the pleasures of the flesh was how holy men became holy. And this coming from a religion whose central miracle was about someone who was tortured to death to bear the punishment for every bad thing ever committed by any (or some, depending on your denomination) human being, ever. Hardly surprising that Christianity has one of the sourest outlooks of any religion.
I don't deny that it's the Puritan tradition of rejecting anything that they consider sinful (drink, adultery, violence) that creates much of the backlash against games - but I don't buy for a second that they consider fun to be a sin, or that social class enters into it at all.
