If you study the real history of Russia and China their histories are much more violent with many less human rights than America

 If you study the history of America you see that without snipers with Muskets the Revolutionary war wouldn't have been successful.

Also, because we were separated from larger areas like Europe and China and other large nations if someone wanted to fight Americans they might all drown trying to get to us in a storm with their ships crossing the Atlantic or Pacific Ocean.

So, generally speaking America was created with a minimum of Violence (except for the Revolutionary war and the Civil War) and you could also say Americans were somewhat violent against Native Americans and that 90% of the native Americans basically died of Smallpox and other diseases brought over through settlers from mostly Europe.

So, generally speaking Americans are a less violent group of people than other nations like Russia and China have been.

The real difference is that people generally have had more human rights without a king or emperor ruling them in the United States. So, in this environment our people prospered with less violence and repression than in other countries around the world like Russia and China and also Europe.

But, when Europe saw how wonderful our system of government was they tried in their own ways to emulate our Democracy in a Republic as much as possible.