There’s a very easy way to reduce injuries in football and that’s to eliminate the helmets and padding.
Without that equipment it would be impossible to inflict serious damage to an opponent without inflicting damage to oneself.
Rugby is a very similar heavy contact sport to football and all they wear is cotton jerseys and shorts (and boots of course). The professionals suffer broken fingers and lose teeth on odd occasions but they never suffer the serious damage inflicted on football players.
This is particularly relevant to the high school game. Remove the helmets and padding and the serious injuries will all but disappear.