Who Sinned?

Our Father our King we have sinned before You -- Rosh Hashanah Confession.

Why does the individual say "we sinned" in plural?

A passenger on a boat once noticed another passenger drilling under his seat. In astonishment, he bellowed "what are you doing?" The other responded, "Mind your own business. I’m drilling under my seat. I paid my fare, and this is my seat." The man said to him "Fool, don’t you realize that if water comes in under your seat we are all doomed!"

The Talmud1 says that all Jews are responsible one for another. The reason for this is that the Jewish people are like one body. Thus, the Jew who sins affects the entire Jewish nation. Likewise, when a Jew does a good deed it has a good effect and benefits the entire Jewish people.2