Bro, the fact is, games are a sport. It is all about tactics, strategy, and hand/eye coordination (not to mention the coffee intake you have at gametime). If I practiced every day for a year at football, will i throw like Dan Marino? No. If I practiced every day for a year at basketball could I jump from the free-throw line and dunk like Jordan? No. But, the frustrating thing is, there are people gifted enough that can seemingly do it right off the bat, with little or no effort, and this inherently applies to gaming as well. Yet, to answer another of your questions, yes there are a LOT of cheats, hacks and such that many who feel as frustrated as you do resort to using, because they are no real competition for the guys who've been gaming for countless years and hours. It's sad, really, but true. It's basically like the basketball scenario: I play Jordan, I lose. I play Jordan with a hack that lets me jump to the ceiling and make every shot even if i'm pointed the other direction, well... Keep your head up and keep chuggin' along. You'll get better before you know it.
Presicely, ive been playing things like JK2 and Quake3 since release and i suck :D
the total amount of gaming in your lifetime makes a big difference. if you always play FPS then your aim with a mouse gets much better, and this carries over between games. while it is true that inherent ability differs from individual to individual, the most important thing is practice. if you really want to be good then you have to spend ungodly amounts of time playing the game, like anything else. example - my roommate plays about 10 hours of rocket arena everyday, and that's just average. on weekends and holidays he does nothing else. =)