I played in HS and coached HS and MS football for many years. I had some injuries, but nothing that has been bothersome as I got older. I was lucky to an extent, but part of it was learning to play aggressively with good technique and being in good condition. I've had teammates that suffered severe injuries, some that plagued them as they aged, and some players likewise. Football isn't a game that you can play half-assed from the standpoint of being aggressive, using proper technique, and being in good shape. Falling short in one or more of these areas IMO leads to a lack of success and worse the potential for injury. Where we fall short is in properly trained coaches sometimes and those who lose perspective where wins and losses are concerned and put the players' well-being in terms of training, physical, social and emotional development at risk. But on the other side, you have kids who would rather and are allowed to spend a majority of their spare time vegetating with electronic stimului. Declining participation is not surprising.
I spoken about this before, but my son played football from the time he was a 5th grader until his last game as a senior in HS. We never had to beg or force him to play. He tagged along at the field some when I coached and grew up loving the game and wanting to be a player. He was fortunate to get some instruction from dad and was a good student. He learned and applied the principles of good technique, had a good motor (played hard and displayed good sportsmanship), and worked to stay fit. He had a few injuries, but nothing severe. He was lucky like I was, but I attribute it to a good foundation. He was a pretty decent QB, but excelled as a SS and would strike you with proper form. One thing we didn't allow was specialization in a particular sport. Early on, he played t-ball, basketball, and soccer. From MS through HS he played football, baseball, and basketball. His was a small school, so he was able to play all three. We avoided travel baseball, though he played during the summers from his junior year on with a group out of Marianna that traveled minimally and he never missed summer football workouts. He stayed in good shape year around, had no overuse injuries, and never felt burned out on one sport. This was important also.
I'd love to think that football can provide more benefits than not to every kid, but all are not predisposed to the game. The important thing is that kids play some team sport(s), as there are too many valuable lessons they can learn through participation and teamwork.