Have you ever wondered why we have a "C" in the English language? After all, it makes no unique sound of its own. It just hangs out in the alphabet looking forlorn and useless. Is it some missing link left from an imagined evolutionary past?
Some people teach that this apparently useless letter has a hard sound and a soft sound. That method is an unnecessarily difficult and complicated way to present the letter sounds. C just copies the sound of S or K. [Academic Associate students know the simple rule as to when it will copy S or K - which works in all but 13 words. This is a very important rule considering about 25% of words in our language contain a C.]
So why do we need a C? When we combine the C with an H we DO make a unique sound. Without a C we would go to Hurch instead of Church, we would listen to a Hime instead of a Chime, etc. So the C is indeed a very important letter and has no reason to feel ashamed because it makes no sound on it own. Like a man and a women come together to make a unique "sound" in their marriage, so "C" marries "H" to produce a special combined sound.
CH itself has three different sounds. It makes its own unique sound as in choose, it copies a K as in Christmas, and it can copy the sh sound as in chef.
As you know, English often borrows and/or builds on words from other languages. The origin of words containing CH can usually be determined by the sound CH makes. If it makes its own unique sound the word comes from the English language. If the CH is copying the K sound, the word originated in the Greek language. And if the CH is copying the SH sound, we borrowed the word from the French.