In the paleolithic age, instead of farming, we hunt for food and gather things like berries, nuts and seeds, We haven't yet discovered that we can plant seeds to grow crops. We move locations often in order to find more animals or plants.
Pretty soon, we learned that we could plant seeds to grow our own food.
Nom nom nom
Eventually we started to domesticate animals. We used these animals to get milk and meat, and trained them to work for us.
Agriculture is important because it makes it much easier and safer to access food! We don't have to hunt for all of our food!
Agriculture was also important because it allowed us to stay in one place instead of having to travel to find food!