I however did know and had the honor to serve with an acutal US Army Corporal. His Corporal orders were issued and signed by the Secretary of the Army and he was awarded the Soldiers Medal for actions while he was a PFC MP at a parade. A drunk driver was running from the police and ran an MP blockade set up to control access to the parade. The soldier saw the on coming vehicle and remained in the street to clear the street including tossing a child out of the way of the on coming vehicle. He was struck by the car and had to spend 9 months in the hospital repairing his legs and pelvis.
For those that don’t know the difference, a Corporal is considered a non-commissioned officer where a Specalist 4th Class (E-4) is not.
You’re right, there are a few corporals. I was in a combat MOS (Combat Engineer) and I never saw one. Until I made SGT (E-5) I was a glorified private.