Mathematics texts have been found that are quite ancient. Babylonian texts from 1800 B.C. and Egyptian texts from 2000-1800 B.C. have been found. These texts have information about the Pythagorean theorum, a widespread mathematical concept. Greeks refined mathematics with deductive reasoning and using proofs. Chinese math included a place value system and Hindu-Arabic mathematicians in the first century A.D. invented a numeral system that is still in use today. Mathematics has evolved over time and continues to do so as concepts are continually expanded upon.
There was no single person who invented mathematics. Mathematics was used, and technically invented, by many cultures around the world. These cultures used their own form of mathematics, which could be considered 'math' in their time and how they used it. These cultures include the Mayans, Indians, Greeks, and Chinese, India and Greece. These forms of math spread throughout the world, and eventually became the math we know today.
Well technically no one has ever invented math but I know that the Greeks had started a way of counting numbers.