There are many different explanations for the origins of this word. Like when you’re playing snakes n’ ladders and you get on a snake square, you get to start all over again by going down. Some say that it originated in that game of snakes and ladders but others believe it was football commentary that created the word.
This theory says that the word was invented thanks to BBC Radio Commenting on soccer games. The station gave maps to listeners so when they talked about the game they had a better idea what was going on. When they said the ball is back to square one it meant the ball was near to the team’s goalkeeper so they had all the pitch run over to attack.
There are many other theories but to be this one seems the most reasonable. Football(soccer) has always been big in England and fans always want to know what’s going on with their team, so the map part seems very plausible to me. This occurred in the 1930s.