Interesting football history: How the forward pass was created in response to the nineteen -- 19! -- people killed playing football in 1905 alone
The original rules of football did not allow forward passes. The ball was primarily advanced by running, with blockers forming lines with interlocked arms and just smashing into the similarly-interlocked defensive lines. It was basically Greek hoplite spear formations but with a semi-spherical ball. As calls to ban the sport entirely grew, some looked for ways to de-emphasize mass charges as the primary means of advancing the ball, and some specifically championed allowing a passer to throw the ball forward.