What is chinua ahebes overall purpose in using igbo proverbs in things fall apart?

There are various reasons for this. One is that he is writing about Igbo culture, so there are some Words that do not translate directly into English. At other times, a translation into English would provide additional unwanted subtext that a Word carries in a specific language. He also wishes to highlight the differences between the Ibo culture and the English culture, noting that they have different instruments for example. Their gong is not just a gong, but is a ogene. In this way he shows that there does exist a complicated culture among the tribesmen.