Things that comes to my mind if circle shape was not discovered or invented:
1. There would have been no tires or wheels created, and transportation would have become tough.
2. Sports like football, cricket, tennis, table tennis, snooker pool, billiards, handball, basketball, golf, etc. and all those games that included round objects could not be played.
3. Alphabet 'O' wouldn't exist!
4. Bottles would have existed without caps.
5. There would be no full moon appearance.
6. There would have been no round clocks, round cakes, etc.
7. Number '0' would not have existed.
8. Round Bangles would not have existed.
9. Round clocks would not have existed and much more.