Rights probably exist because hand weapons of even the most basic sort (gazelle femur) make the naked ape orders of magnitude more lethal than he was before. This turns the game of bullying one's fellow naked apes from a straightforward process of picking on smaller into a very dangerous games for all parties. Once you reach the level of the pointy stick, even the smallest and weakest adult male in the group has a good chance of ventilating your intestines in a fight if you push him. Some rude respect for his rights becomes prudent, at least until society becomes over-organized and "leaders", states, and organized armies of goons make baboon-style tyrants possible again.
Thank the apish man who invented the club. Thank Colt for the reliable repeating portable firearm. Together, they did more for "equality" than all the philosophers and statesmen in history.
One of the most adaptive traits of humans is probably the extent to which we do *not* dominate other humans. Ugg and Grugg are more likely to stand and fight off the saber-toothed tiger with Mugg if they have a hearth, woman, and whelps to defend as well. "We few, we happy few, we band of brothers." If Mugg managed to monopolize all females and resources (ignoring for the moment the fact I mentioned about the likelyhood of Mugg ending up stabbed for his trouble), it is quite likely he'd get slack help from those with no stake in the game.
I don't really buy pseudo-Freudian "phallic" theories. It is entirely probable that apes who fought their way to the top of a food chain using weapons and tools have an instinct to be fond of weapons and other tools in and of themselves, without referencing the sexual instinct.
EDIT: And I guess the thing about chainsaws is that most of the movie audience doesn't actually use one all that often. If they did they'd see it as a somewhat temperamental and heavy tool that is very ill-suited as a weapon, instead of a magic sword. I haven't experimented with this (for obvious reasons), but I've always felt like one blow with a heavy bladed weapon would be likely to sever the chain on one and leave it useless.
They're all phallic symbols with the capability of delivering massive catastrophic damage. It's all about dominance and power, even if it's just a subconscious connection. You can't just turn off millions of years of evolution by writing down a philosophical treatise about "human rights", even if those rights are enforced as the law of the land. The body and brain chemistry that made humans "win" the scramble to the top of the food chain is still there, and it's all about surviving with a competitive position of advantage when looked at over the very very long term.
So... phallic symbols that invoke images of dominance and power are going to seem "cool" to most men, even if they don't know why. And of course hollyweird is gonna do whatever it takes to sell tickets, so they go looking for these icons of power and use them to sell movie tickets.
