Very anthropocentric. Sure, the way we use our hands may have contributed to our ending up this way but that doesn't suggest that opposable thumbs are the only way to skin a cat (ask a dog). The best we could say, if it were true, would be that it's one way to get where you find yourself. Dinosaurs, in their 160 million or so years had to deal with a variety of environmental variables, and thumbs are useful (see: Troodon). This should tell us that thumbs and weather does not a wise creature make - in and of themselves.
I am the Infantry. I am my country’s strength in war, her deterrent in peace. I am the heart of the fight… wherever, whenever. I carry America’s faith and honor against her enemies. I am the Queen of Battle. I am what my country expects me to be, the best trained Soldier in the world. In the race for victory, I am swift, determined, and courageous, armed with a fierce will to win. Never will I fail my country’s trust. Always I fight on…through the foe, to the objective, to triumph overall. If necessary, I will fight to my death. By my steadfast courage, I have won more than 200 years of freedom. I yield not to weakness, to hunger, to cowardice, to fatigue, to superior odds, For I am mentally tough, physically strong, and morally straight. I forsake not, my country, my mission, my comrades, my sacred duty. I am relentless. I am always there, now and forever. I AM THE INFANTRY! FOLLOW ME!