Lately there's been a spate of hatchery chicks not reaching adulthood, or more to the point never growing out of chick stage and size. A lot of them are about as feathered as yours, even at a year old, if they make it that far. If hormones guiding growth are not working then other failures will be occurring. Yours may be one of those permanent babies. I don't know if kelp will change that but it's about the best thing I can think of that stands a chance.
About the breeds, they look correctly named to me, though my skills at identifying purebreds as chicks is limited since I keep mongrels. About the genders, I think you may not have hit the female jackpot there... If my best guess is even close to right. At my most liberal guess I would say 3 are females.
The leftmost one looks either well-developed female or less-developed male, crestwise and colorwise. Not 100% sure about it.
The one closest to the camera, male for sure.
The one furthest away, in the back behind the other two, definite male.
The one furthest right, also male.
Really only the two standing in front of the boy in the furthest corner look like probable females to me, lol!
...But I could be wrong.
The more I look at the two I think are girls, the more I think the featherless one might just be a very under- developed boy, and the other one in front of that one has quite a wide crest for a girl, but it's not that male in appearance either, and neither are the wattles... Is she still wearing her eggtooth? Her beak looks strange.
Also the male that's furthest right, what's going on with his primaries? Is his wing wet?
It's a good thing you wanted pets, I hope you have the space for roosters or someone to take them to a good home. Sadly I think you're been sold a very scrappy bunch, I wouldn't breed them if they were mine. The legs are quite incorrect, the leg bones and scales show inherited splay leg genes and malformed bones, and they don't look like their parents were well chosen nor well fed, in my opinion. I'm sorry. Hatchery chicks always seem to be such disappointing news. But as pets they may excel. Roosters too can be great pets if you can keep them where you are, i.e. if you don't live in suburbia. Contrary to popular belief they can enjoy one another's company and live peacefully together. Wish you all the best with them.