It was because you referred to “humans”, as if distinction was required from a larger group. Nothing more than that, sorry for the confusion.

I see .. might have been because english is not my first language, but I thought the way I wrote was clear and common?

It is very clear. Your English is perfect, but I suppose it is unusual (to me) to see references to “humans”, maybe “people” is more common but there is absolutely nothing wrong with what you wrote.