Just my thoughts. From what I’ve read, I think you’re doing very well with your handling of the cockerel. You’re being patient and this can be a great learning experience. It sounds to me like you have his respect, though never turn your eye, of course. You’re more aware now of positions, such as being lower than him, which could provoke attack. Now, the cockerel, in his nature did this thing, perhaps others would not have. This is notable.
I think the little girl, being unfamiliar to him could be considered a mishap, although some would have a rooster who wouldn’t attack any person, ever. I believe in nature and nurture, not either or, therefore I don’t believe there’s no hope for him. Train, but don’t work too hard at it, that you can’t enjoy your flock, those are your chickens, and he’s very fortunate to get to be your rooster, don’t forget.
Don’t allow him to take over your place!
I believe in giving them a little grace, they’re not always going to get it right. But as they age, you should have the full respect of this rooster, and your boy, and if you don’t after all, well, you gave him a fair chance.
That’s commendable!