From a system point of view, when an understanding of information theory is combined with genetics, then life is an accumulation of information with a measurable per-generation information gain. The concept of "I" is just a consequence of our subject/object language structure and it's looking more likely that language syntax is innate. It's always better to ask "what is the purpose?" of rather than "what is the meaning of?". If you ask what's the purpose of the concept of "I" then the answer seems quite clear to me.. to enable communication. This can also be viewed in an evolutionary context.