[avz]

The perspective of modern computer science (with its zero-based indexing etc) or modern algebra (with its need for neutral element for addition) certainly makes it clear that zero is just another integer. However, without those perspectives I doubt it is so obvious.

For example, people normally count things by starting from one, so, at least following this usual procedure, counting to zero is technically speaking impossible. Also, we can't distinguish between zero apples and zero oranges, but we can tell two apples and two oranges apart.

In fact, even with the perspective of modern algebra zero remains special. For example, it is the only element of a field without a multiplicative inverse.

I'd be surprised if zero didn't take any extra effort to discover. It's clearly different than other integers.