In the ancient world, the stone age human being evolved gradually as time progressed. The man started to do a crude form of business or trading. It was by the Barter method by exchange of goods.
There mathematics became important and counting was essential in the business, earnings and savings. Counting was done by using integers. This is the first and best use of integers. As man learned to measure, distances were expressed in integers and their ratios. So was the time of the day. It was expressed in integer form. Persons ages were expressed in integer form.
As the field of mathematics, commerce and sciences developed, integers formed the basis of all other quantities, for measurement, comparison, and computation. Integers allow us to specify any quantity to another person precisely in stead of some qualitative measure like : so much/something/ a little / large etc.
Finally, in today's world the integers or the figures as we call them, are the basis for decision making by the big business executives.