Language is almost certainly an invention of the rational mind (seated in the neocortex of the human brain), and it is most probably the only part of the mind that can use words to think. I would guess that other parts of mind use pictures, patterns, or symbols as tools of thought rather than using words.
Words are extremely abstract – a combination of sounds to designate a specific concept (an abstract of mind to indicate some aspect of reality). It is not necessary to use words when thinking, but words certainly help us to communicate with each other.
I would think that very primitive organisms probably start of by differentiating between levels of light and dark, cold and heat, or muck and food (feeling, taste, and smell). The next step would be that of discerning different forms (a primitive eye) and then perceiving patterns (repetitive forms) in these forms.
Your dog, and/or cat, can ‘read’ your intentions and feelings very clearly, by observing and analysing the different patterns you weave into your daily live, and vice versa. Just but ask any pet owner.
An early way of understanding and thinking rationally would be by using symbols. Symbols can then be the start of language. I think that the different layers of the human brain still work in this very way.
Life is much about patterns and hierarchies, and the encoding of these patterns and hierarchies into symbols and language as information.
However, language is an extremely limited artefact to use in communication. Whatever I experience is my ‘pattern that connects’ me to reality, and to explain that to somebody else I need language, art, mathematics, et cetera.
However, no means of human communication is truly adequate to explain reality; we can but only approximate by mapping (or modelling) reality.
Your physical experiences are already very tough to communicate to somebody else; your emotional experiences are even tougher; spiritual and mystical experiences are impossible! Other people’s inner experiences unquestionably exist, but they can never be observed by our ordinary senses.
This then is my problem: How do I communicate with you about concepts like life, spirit, the soul, mind, and consciousness? How do I communicate about God, reality, love, and my pain and joy? The only way I can think of to communicate with you (especially over distance and time) is by means of the very restricted lingual apparatus of analogy and metaphor.