No innate ability to change is not evolution for many reasons. Its not triggered by selection or happenchance mutations. Its instantly a adaptation perhaps even in the womb of a mother without the adaptation.

I know all claims about folks not changing now.
Yet the change did happen quickly so we merely surmise that human bodies after the flood wre more sensitive to adaptation. Of coarse since we needed it god would of provided the mechanism. I have siggested before that the oringinal bodies did not have the colour fixed in our skin. Our skin perhaps was very different and flexible to any change. like a chameleon maybe.
Only after the flood did our bodies have more severe needs and more severe skin change results.
We needed to get light to get the sun or we needed to get black to protect from the sun. like your rickets example.
Our bodies perhaps don't change today for the reason they are in a fixed state. originally we were not and things being more primitive we couldn't take care of ourselves.
Human bodies are the great example of quick adaptive change that is innate just as I see it in animals.