This is a simplified explanation of Q and QU (because I don’t know Phoenician or Hebrew), but it makes sense to me.
According to etymology.com:
Q: 16th letter of the classical Roman alphabet, from the Phoenician equivalent of Heb. koph, which was used for the more guttural of the two “k” sounds in Semitic. The letter existed, but was little used and not alphabetized, in Gk.; the stereotypical connection with -u- began in Latin. Anglo-Saxon scribes adopted the habit at first, but later used spellings with cw- or cu-. The qu- pattern returned to Eng. with the Norman Conquest. Scholars use -q- alone to transliterate Sem. koph (e.g. Quran, Qatar, Iraq).
Apparently, the two sounds (roughly k and kw) were transcribed as k, c, and q and kw, cw, and qu, depending on the language, the era, and the scribe (Latin favoring qu and Anglo-Saxon favoring kw and cw. As the influence of Latin became more prominent after 1066, the English language inherited that preference. (Note that kw and cw in spelling are all but non-existent.)
The confusing part comes with words like pique and oblique, which have the qu spelling but the k instead of kw sound. You can either remember that most of these are French, that there is a similarity between qu, gu, and ck (all of the second letters help retain the hard consonant sound) or spell them with a qu just because your chances of being right are much greater,
