Today My Son Got Hurt Because Of My Parenting

My son was at the playground of the vaccination center, chasing after the ball.
Two bigger boys jumped in front of him and started hitting the ball and took it with them. My son ran after them, bumped into a rocking horse, bled his lips, and cried his lungs out.
I was 2 feet away from him, and I watched everything.
I had good intentions though.
I intended to let him play with other kids so that he could learn a thing or two about social interactions.
I intended to let him fall and get back up on his own feet.
I intended to let him learn how to cope with the environment so that he could be independent.
I intended to let him play with other kids so that he would learn how to work with other people.
I intended to let him do whatever he wanted and learned from his lessons.
I intended not to overprotect him so that I would not cut his wings and smash his dreams by ignorance.
I intended…
And his cry woke me.
Why would I stand there and watch him chase after those boys, even though they were much bigger than him?
Why would I watch him fall and get hurt?
Why wouldn’t I protect him until he is big enough to protect himself?
Why would I let things like that happen?
Did I love him enough? If I do, what was I thinking?
That night, I lay on the bed and watched my son sleeping, I was consumed with mom guilt.
And I questioned myself. What should I do now?
Follow the books I read about children interactions, child development, and just let my son be? Allow him to fall and get back up? Let him possibly get hurt and learn his lesson?
Or should I protect him from the world, never allow anything to touch him so that he will never get hurt?
Should I take him away when other kids take his ball? Should I take the ball back for my son on his behalf? Should I intervene in the children's game to make sure my son gets the best part?
Do I worry about my son’s development when keeping my son away from other kids?
I do. So I should allow him to play with other kids.
Do I worry about my son getting sick or getting hurt because of that?
I do. So I should not allow my son to play with other kids.
There is an endless list of questions in my head, concerning my parenting if I’m doing the best thing for my son.
Raise a warrior or raise a prince?
Tough question. Even I have different answers on different days.