C 130 1 is the main contract, and c 12 1 1 is not. The main contract of agricultural futures generally ends with 0 1, 05, 09. For example, the next main contract for corn is c 1305, the next one is c 1309, the next one is c 140 1, and so on. This is true for soybeans, soybean meal, wheat, sugar, etc.

As for why there are only a few contracts, it should be a matter of habit or convention.