Do you know how many 1st person pronouns are there in Japanese? I looked it up, and the answer is unknown or too many.
I agree. Even frequently used ones are abundant. In addition, the dialects of the pronouns are countless.
Though there seems to be too many choices, if you are learning Japanese language, you may have only one word to mention yourself.
watashi（わたし・私）
If you are a grown-up, this one is most recommended and maybe the only choice. Watashi is usable for men and women, regardless of age as long as you are an adult. Watashi sounds too polite to your friends. In this case I use ore.
boku（ぼく・僕）
In spite of the fact that boku is a first person pronoun for boys, some Japanese male adults call themselves boku in public. I cannot say why, but this makes me uncomfortable and think to myself “Why not watashi?” Among your close friends, it is OK to use boku.(personaly, still uncomfortable)
Some girls or female adults also use boku. Many Japanese songs contain such lyrics. You may have seen girls in manga use boku. These usages do not necessarily mean they want to be boyish.(I guess)
Is she likely to call herself boku?
ore（おれ・俺）
Ore, which sounds kind of rough, is usable for only men. While I do not use it in public, I do among close friends.
While boku is sometimes used by girls and women, ore is never. If a female person calls herself ore, she surely has an intention that I do not understand.
