Yes, the first headphones were single-earpiece devices, called monaural headphones.
These early headphones were used for telephone switchboard operators in the late 19th century, allowing them to listen in on telephone conversations.
The single earpiece design was practical for this application because it allowed the operator to keep one ear free to hear their colleagues and the environment.
These early headphones were heavy, uncomfortable, and had poor sound quality, but they paved the way for the development of modern headphones.