>Can you imagine if someone shot a person and then claimed that they didn't understand how to use a gun and so they accidentally killed a person and then proceeded to accidentally cover up the "accident"?

First, it depends on what they're charged with. Because if they're being charged with murder, they can absolutely argue they didn't understand how to use a gun. Generally, when charged with murder they need to prove you intended to kill. If I fire a gun at you and just meant to scare you but happened to nail you between the eyes, then in many if not most states, it's not murder.

Depending on the charges "mens rea" can be the difference between jail for life and time served with a fine.