It sounds like this little one was born with a neurologic problem that makes it impossible for her to control her limbs.
This can be a brainstem issue called cerebellar hypoplasia and is caused by the queen being infected with a virus during her pregnancy causing permanent damage to the kitten's brainstem. In mild cases the kittens learn to move around but will often have a tremor especially when excited or trying to eat. In severe cases the kitten is unable to walk at all and it makes nursing difficult as well which could lead to a kitten with small size and poor condition.
In some cats with short or no tails there can be spinal cord problems which affect mobility as well.
Abnormal parasite migrations can also affect the brain and spinal cord. Toxoplasmosis is a protozoa that can affect the brain and spinal cord. Toxoplasmosis is a zoonotic, meaning people can get it from handling an infected cat's feces when the parasite is initially picked up, so I do recommend testing her for that and other parasites.
Immunosuppressive viruses like feline leukemia and feline immunodeficiency virus can also create neurologic issue in some kittens.
I highly recommend testing her for those viruses.
I highly recommend this little one have some tests run to make sure that we cannot help her in some way. In the meantime vitamins for kittens may help, look for one that has taurine in it too because that is important for proper brain and spinal cord development.
If this is cerebellar hypoplasia most of these kittens improve with time. The brain doesn't heal, but they learn to compensate and adjust the way that they move so that they can eat and comfortably get around. This is not painful, and she may be able to live a happy life as an indoor only kitty.
Please let me know if you have any further questions.