I'm firmly in the camp that math is invented by humans. It is a model of reality, not reality itself. Look up Gabriel's Horn paradox or the Banach-Tarski paradox.
Gabriel's Horn is a particular infinitely long straight trumpet and it is possible to prove that it has finite volume but infinite surface area. It requites an infinite amount of paint to paint the outer or inner surfaces of the horn (it has no thickness). However, because the volume is finite, it is possible to fill the horn with paint. Once you dump out the paint, have you not painted the inner surface?
The Banach-Tarski Paradox says that it is possible to take a solid sphere, break it up into parts, and then reassemble them into two solid spheres of the exact same size as the original. It is possible to prove this without much difficulty, but one cannot do this in reality because the disassembly would require an unaccountably infinite number of impossibly complex cuts.
Also, many aspects of mathematics are arbitrary, it could have been invented in other ways. Although the differences would mostly be inconsequential.