In some countries, zero is neither positive nor negative. But in other, it is both positive and negative. So saying the set of natural number is the same as non-negative [integers] doesn’t really help. (Also, obviously not every would even agree that with that definition regardless of whether zero is negative.)
Definition of natural numbers is the same as non-negative numbers, so of course 0 is a natural number.
But -0 is also 0, so it can’t be natural number.
In some countries, zero is neither positive nor negative. But in other, it is both positive and negative. So saying the set of natural number is the same as non-negative [integers] doesn’t really help. (Also, obviously not every would even agree that with that definition regardless of whether zero is negative.)