No-one has mentioned Latin, but the 'qu' structure in English basically comes from that language. In Latin, the 'kw' sound was represented by 'qu' in words such as 'quis', meaning 'who' or 'quo' meaning 'where'. The French took it over but do not now pronounce it as 'kw'; their word 'qui' (who) is pronounced 'kee' not 'kwee', for example.
In Old English, this kw/qu sound was represented by 'cw' in words such as 'cwene', meaning 'queen', as suggested above. After 1066 and the Norman Conquest, 'qu' began to be used alongside 'cw' and by the end of the 13th century it had replaced it entirely. So, the 'qu' form has existed for over 700 years now.