Regarding "guys".
Originally:
Singular == thou
Plural == ye
After thou disappeared, we started inventing replacements for a clear plural:
y'all
yous
you lot
you people
you guys
"You guys" became the plural grammatical solution, representing both males and females.
"man" in "all of man kind" does not refer to males. It's Old English:
mann = person
wer = adult male
wīf = female/woman
wīfmann = female person
↓
woman
wer + wolf
↓
werewolf
Sidenote on "guys" next...
Potential versus non-local quantum Fields explained:
* In 10 years. Find out if the electrons probability of being in any location had any influence on this theory
https://t.co/Nzu0B4rFVt
I always believed that "Curiosity killed the cat". But my environmental human inputs were paraphrasing. The full idiom is:
“Curiosity killed the cat… but satisfaction brought it back.”