I stumble upon the word '俺' when my mom was talking to someone from a different region of China but the dialect was still the same. 俺 and 我 both mean the same thing right?
I always think of the Monkey King when I hear 俺。
Why does the Monkey King call himself I, Old Sun (俺老孙）?
俺 and 我 are the same meaning,
also 孙悟空's surname is 孙,
add to that he is relatively old,
several hundred years,
(when) he sees an evil spirit he automatically calls himself I, Old Sun (俺老孙）