My children are older (my youngest is 8), but I'd be very careful with little ones and roosters. If I had children that little and roosters, they would be fenced off separately for both the protection of the child and the chickens.
My chickens are fenced off and my rule is that I must be present when any child goes in my runs. We've had some friends kids want to go in to see the chickens, but I have to be with them. My youngest likes to go into the run with our young roosters (4 of them at the moment) and squat down to watch the chickens. These cockerels are 21 weeks old, and the hormones are just starting to kick in. I told him at one point to stand up as one of the cockerels came close to him (NOT in an aggressive manner, just looking for treats) - he did and the cockerel instantly retreated. I'm teaching him to treat them the same way I do - walk through them, not around them. But he's never allowed in the run without me.
I can tell you from firsthand experience that a puncture wound from a spur hurts like heck. (and bleeds a lot too) I've also had a rooster not break the skin, but he broke a vein in my leg and gave me a bruise the size of a softball. He also hit me at waist level once, and I'm 5'8. I still don't know why he chose to go after only me, he was fine with my DH, my kids, strangers, etc. But he would come at me every chance he could. I tried everything to reform him and nothing worked. I got tired of watching my back every second in the run, so he's not here anymore.
The slightest thing can set a rooster off. Could just be your child picking up a hen and it squawks - the rooster could come to her rescue. It's what they are supposed to do. My welsummer rooster is a perfect gentleman, both with me and with my hens. I have been flogged by him once. Turns out he doesn't like cell phones.
The first time he flogged me I was talking on my phone in the run. The 2nd time I came in with a cell phone, he started towards me - so I instantly hung up and he backed down the second the phone was gone. I now do not carry my phone in the run, and I haven't had a single issue with him since.