In some ancient languages, the word for God (which is actually the 3rd person in most of the modern languages) is called Primary Person; second person is called Middle Person, and the word for “I” (which is actually first person in most of the modern languages) is called Perfect Person. This wording conveys the understanding of ancient people:
“When God is viewed as Primary Person, or put above everything else, and
When I deal with another person as if he is in the Middle of me and God, or under the watchful eye of God, and act with pure motive,
I become Perfect in the eyes of everyone—God, other humans.
When me-first attitude appeared, “I” is called First person in most of the languages, and God was pushed into 3rd person.
Here is another case of evolution—a modern word gay! How did this word meaning joyful come to refer to homosexuality? http://www.wordorigins.org/index.php/site/comments/gay/ traces an interesting history.