Humanity does not meet the criteria to be classified as an official religion. A form of it could be if it were organized properly, and it probably already is. However, humanity itself is just a way of being. It is like saying meditation is a religion. To some it is, but not really...
These are two different things. Humanity is the larger category to which we all belong. Religion, along with other cultural practices, is a subcategory of being human. Humanity itself is not a religion because it does not say anything about our attitudes or beliefs toward being human and religion does.
Unfortunately, humanity in itself doesn't meet the criteria to be classified as a religion. Every human being is a part of humanity, and there is no set beliefs or values associated with humanity. It's nothing like Christianity or Islam or any other religion, so nobody should consider it a religion.
Humanity is a term that can refer to humans collectively. It is also defined as meaning humanness or benevolence, but I find these terms far to broad to be easily interchanged with religion. Religion usually includes a set of beliefs, along with rituals. Humanity does none of these things and I do not believe it meets the criteria to be classified as a religion.
I do not think humanity alone can be considered a religion. It is a way of life, it is who we are and defines what we are not how we believe and think. Humanity is just what we were made into when born and does not mean it is a religion.