No, it's not ME claiming that we are all sinners, or mass-murderers. Listen to a good-old fire and brimstone preacher telling his flock how evil and perverse mankind is, and that will tell you who thinks we are all sinners. And they get it from the Bible.
What I am saying (and it's all hypothetical, since there probably is no God) is that God made man with the CAPACITY to sin, which makes man imperfect. And if we are made in God's image, then God also has the capacity to sin, which makes HIM imperfect.