Well, with 4 boys, we are a football family. My 2 older boys played all through high school. My 2 younger boys are freshman next year and are playing - 6am practices started the day after they got out of school!
However, they did not play tackle when younger. They played flag for years and years. That being said, there is no protection in flag football (or soccer) and it's still a close sport where there IS contact, even if against the rules. The last year my twins played flag they ran smack into each other on a play and one had a concussion, one had a torn lip and was gushing blood from his nose (so fun having 2 insured at the same time! Not.). If it had been tackle, they would have just gotten up and continued playing because they would have had helmets and pads on.
And I do understand serious injuries can happen with football, but a lot of precautions are taken with learning to hit correctly and our school has concussion baselines done before they start playing. And really, kids can get hurt in any sport.
Check out your community and see if they offer tackle at that age. They do here. And if it's something he enjoys, he'll be ready to play when it's offered in school.