Tunics - The Ancient T-Shirt?

I have, well need, to retire some well worn and love tunics that I have had in my wardrobe for years. It is torn and full of holes. So, I sewed two more this week for replace them.

I will have different photos later.

Some history about tunics:  Following the fall of the Roman empire, the tunic continued to be worn with varying sleeve and hem lengths throughout Europe during the Middle Ages. Often reaching the knees or ankles, it was usually worn over underclothes consisting of a shirt (usually hip-length or longer) and drawers (usually knee- or ankle-length pants related to braccae). It may be accompanied by hose.

I found it interesting that a tunic worn as a regular shirt in modern times was worn as underclothes in ancient times. Were tunics the ancient T-shirt?