On some level, the most basic of communication between human beings had to reside on an emotional level. The role of communicating emotions in the very beginning of humanity's origin had to reside in the communication of needs, wants, or desires. From the most metaphysical point of view, human beings wanted to communicate something that resided in the base of emotions. If one examined how individuals needed to convey something that was within them, it becomes readily evident that this had to be a communication of human emotion. Even the need to want something is an emotional one. If we really delved into the metaphysics of this, the only reason one communicates with another is through an emotional frame of reference. The first form of language between two people resulted in a need to be validated or acknowledged. It resulted from a desire to be authenticated, and this is an emotional need. The first human language was driven by emotions because it was one of the first instances where people were able to articulate something understood by another and this had to be an emotional sensibility for those are the elements that most readily needed communication. Interestingly enough, those are the domains that are hardest to convey. This means, that the most pressing need to communicate, an emotional one, constituted the first language, something that is still being refined today for putting one's emotions into language is still incredibly challenging.
Of course! Yet do you mean the first human language as in an infant? Or the first human language as in society? Actually the answer is yes for both. Imagine what the child is communicating, their immediate needs and how they feel about them. Isn't almost all forms of communication trying to convey needs and the emotions that go with them? Human nature has the need to communicate how they are feeling about any situation. Our innate make up requires us to communicate with one another and make our thoughts and needs known to others. The need to share our feelings is so strong it has always been of paramount concern in society. Think of Facebook or twitter, the sucess of these social networks are derived from the fact that humans need to communicate their emotions. I am not sure if I answered your question because "1st human language" could mena many things.