The term "port side" originates from the fact that ships used to dock with their left side facing the port (or harbor). It's like when you always park your car on the same side of the street, just out of habit - ships did the same thing, and the term stuck. This was also a time when ships had a starboard (right side) steering oar, which made it easier to dock with the left side facing the port.
In the old days, ships didn't have fancy docking equipment, so they relied on the tide and the wind to help them maneuver into the port. It was like a big game of maritime Tetris, where ships had to fit together in a specific way to avoid collisions. The port side became the standard side for docking, and the term has been passed down through the centuries.
