I utterly loathe images of peoples' children and pets, but these are really good.
I still don't like them, but that's my problem. For the most part these are technically well done, nicely lit and well-composed, and are extremely flattering to the child. Great job.
I will add that, by comparison, I think the color images are more effective. There's an upbeat sort of liveliness to this kid, which I think is well-served by the warm colors. The black and white images are sort of lacking that, I think. They're still good, I just think they look worse when presented right next to the color images.
Also, when looking at the two black and white images, I notice that the first seems to have a little bit of a warmer tone than the second. I'm also thinking I see a little bit of a green cast (maybe it's just my monitor, but that seems a little weird to me), but I think that warm is the way to go. The second black and white image almost seems a little bluish to me (though again, maybe that';s just my monitor and maybe it's due to comparing it to the other photographs). But in any case, the second black and white image here seems to be the coldest of the bunch. And if you're gonna go black and white, I think the image could stand to be warmed up a little bit.
The feet are my least favorite images here. I see what you're going for, but I just don't think that image has the same impact. With the other images, there's just more "pop". The liveliness of the kid just jumps out, it's very obvious. The feet are a little bit more subtle. They don't really work in the same way as the others. They don't really work so much as a standard portrait of the child, because you can't tell whose feet they are. You need more information: information which I'm sure is available to you as a parent, but is lost to others. To me, they could be anyone's feet. With that in mind, I'd appreciate #5 more if it was shot in more of a "fine art" way. Like, sculpting the feet with light to emphasize the contours in them, or something like that. That, or just accept that critics like me are outsiders, that we don't "get it", and that this image is for a select group (namely, the kid's parents and family).
But long story short, from my perspeective as an outsider:
1) Great images.
2) Color works better than black and white.
3) If you're gonna go b&w, warm tone works better than cold tone.
4) Faces work better than feet.