The Hunting Tradition
Some thousands of years ago, hunting was not a privilege as it is today, it was a necessary means of survival. Humans had to hunt to protect themselves from predators, or they would die. Think about the types of animals these people encountered: Huge mammoths, enormous cave bears, vicious saber-toothed cats. All these animals were stronger and faster than the typical human being. Humans therefore needed to out-smart these animals in order to live another day. They also had to hunt to get food, or they would starve. Taking down a mammoth would mean feeding an entire tribe for days, maybe even weeks.
In the most early days of human civilization, close contact was the only known way to hunt. Humans would use rocks or sticks as tools to take down predators, but as you can imagine this required very close proximity to some very ferocious animals. Then came the idea of using projectiles. Throwing a spear and eventually using a bow and arrows, greatly increased the distance between the hunter and the hunted, which in turn increased the hunter's odds of getting out alive.
Gunpowder was invented in the 13th century, and revolutionized the way humans hunted and fought battles. The very first firearms were simply metal tubes that were closed off on one side. Gunpowder and a projectile (such as a rock, piece of metal, or any other hard object that would fit into the tube) were loaded into the open end of the tube. A small hole (known as a "flash hole") was on the side of the tube toward the closed end, where a match or wick could be inserted to ignite the gunpowder. Hunters or soldiers would hold these tubes with their hands, pointing in the direction of the target.
As you might imagine, holding a metal tube that shoots out a projectile due to burning powder could cause serious injury to those holding them. So, the next step was to add a part to hold the firearm, and a way to fire without having to put one's fingers at risk. Hence came the stock and trigger of a firearm.
When settlers first came to America, firearms were somewhat developed. They came with the first muzzleloaders. These are firearms loaded from the muzzle end, which have a trigger mechanism for firing and a stock for holding the firearm. They fired either a single lead ball, or multiple smaller lead pellets for smaller animals. These were instrumental in helping humans survive in the wilds of a new world.