Could you please tell me why from an historical point of view that when the letter c comes directly before the letters e, i or y in English that we use the /s/ sound, but in other cases we use the /k/ sound? For example, c represent /s/ in city, center, century, cycling, but it represents /k/ in...

This may sound silly. But I'm really confused why, when we pronounce (the phoneme) /k/, we sometimes spell it with a C and sometimes with a K (sometimes with CK). Why wasn't 'k' used instead, in such words as: car, cake, etc...?

TLDR: Because Latin mostly first came to English through French, we picked up the French habit of pronouncing most Latin-derived words with ⟨ce⟩ and ⟨ci⟩ using /s/ or sometimes /ʃ/, but never /k/. We also got into the habit of not changing spellings once established. Below please find ...

It seems to me that the vocabulary tag is mostly superfluous. I found this old post from 2010 which compares the tags words, which has since been rightfully discontinued, word-choice, single-word-requests and vocabulary. RegDwigнt asserts at the end that the words tag is a simple cop-out for so...