Earlier quoted context omitted.
>The same for negative numbers Are you sure negative numbers are not "real" in the same way natural numbers are? That would mean particles like electrons with a negative charge are not "real", too. And someone can argue that his negative bank balance is not "real". As for complex numbers, I fail to see how they are less real than real numbers. Real numbers are points on the real axis, while complex numbers are points…
While negatively charged particles are real, the 'negative' charge is a way to distinguish them from a 'positive' charge. It's a naming convention more than it is an actual negative value. We could easily call them 'black' and 'white' particles and the system itself would stay the same
Don't let the naming confuse you. The name "negative" might be a peculiar, human-specific thing, but the concepts of addition and additive inverses are not.