>economics is the study of something that is 100% man-made, yet we cannot explain many of its aspects. Heck I am more confident in physicists able to explain physics, and mathematicians able to explain mathematics
You could easily argue that mathematics is something that is man-made.
True, but mathematical objects, unlike people, always behave rationally.
If anything, events like negative interest rates simply illustrate how ridiculous the classical economic notion of the "rational actor" is in the real world.
You could easily argue that mathematics is something that is man-made.