(And we are speaking about plane geometry here, although spherical or any other geometry rules also existed before Pithagoras or anyone else noticed them.) Same as 2x2=4 or 1+1=2. These equations can be written in any european / arabic / greek/ mayan or any other alien civilization notation and are correct in ALL of them regardless what symbols they use. Moreover, the fact that 2x2=4 or a^2+b^2=c^2 existed even before any humans or aliens had invented any math notation, it exists even before humans or any aliens.
Take a look at hydrogen atom. It is a solution of Shredinger equation for an electron in Coulomb field (basicly H is elementary harmonics of spherical waves). It is the same solution here, on Earth, and in Andromeda galaxy despite the fact that aliens there have their own notation for Shredinger equation (you do not have to be a genius to understand that their equation thus is mathematically identical to our Shredinger equation).
Same with a photon - it is a solution of QED equation for accelerated charhe, regardless if the aliens write the equations, or humans do it, or NO ONE DOES WRITE THE EQUATION AT ALL.
And Universe strictly obeys mathematical rules (which we call equations) - all objects in it are mathematical solutions of equations (with given initial and boundary conditions).
So, math is RULER of universe, and thus in no way is just human invention.
Human invention do not govern Universe. Take various religions, for example. They obviousely do not rule or shape universe (they do not explain correctly events and phenomena in universe, they can not predict anything in universe) - in contrast, math DOES explain and predict events and phenomena in universe, and math shapes universe - it governs the very existence/nonexistence of phenomena and objects in it.
If some equation has 2 solutions (say, time of fall of a rock thrown in the air is a solution of a quadraic equation and has 2 values - one positive and one negative) - there WILL be 2 phenomena corresponding to these solution (negative time simply means that arriving to your hand with the same velocity vector rock would cross ground level a few seconds BEFORE).
Or, if some equation DOES NOT have a solution, there will be NO event described by this equation. For example, if initial conditions are throwing rock horizontally over round Earth TOO FAST (more than orbital velocity) than there is NO real solution of the above quadraic equation - meaning that that there will be NO such event as crossing of ground level at these initial condition.
Therefore, math is NOT human invention. It existed in universe before humans or any other aliens, it governs ALL events in it, and likely governs creation (better say, evolution) of universes themselves.