There is one star in the solar system, and there are two hydrogen atoms in a molecule of water (H2O)
Picture is misleading, text is accurate

I'm not sure if this r/woooosh moment or not...

*different boing boing*

30, 40 or 50% of the average are quite often a passing grade in Japan.

五 is 4 strokes though:
ー / 7 ー
正 "correct" is just a generally "good" kanji and probably chosen for that reason.

It depends if you include slang/archaic ones, but on the top of my head:
watashi, watakushi, atashi, atakushi, atai, uchi, wacchi, washi, boku, jibun, wagahai, sessha, yo, oira, ware, chin

Japanese has around 18 words for 'I' and as you say they are not about gender, but most are almost exclusively used by one gender.
'Watashi' / 'watakushi' - the standard is used by both genders professionally, but rather uncommon for males privately.
'Boku' is predominantly male 'I', but is very common for women to use when singing.
It's very much context what you can and cannot use.