The concept of maths is invented, but the validity of it has always been there. Things such as the golden ratio and fractals are in nature, but humans just gave a name to it.
It’s difficult to give it a single label – discovery or invention – as both relate to each other. Formulae and theories etc. have been invented by man, but that’s only to discover what is already there. The circumference of a circle already exists, but the formula: C = 2πr has been invented to figure it out.
Currently, I don’t think I’m at the point where I can make an accurate judgment, so I’d have to conclude with – both.