As for Jane/John/Baby Doe, Doe is used as a placeholder name in a legal action, case or discussion for a female/male/baby party, whose true identity is unknown or must be withheld for legal reasons...
It's pretty simple, at the time; Jane was the most common female name, John the most common male name, Doe the most common surname.
Heres what I came across:
In the United States, the name John Doe...
plaintiffs in roe vs. wadeThese are not their real names. John & Jane [ or Mary Doe ] are used to protect people's privacy , and are often used when real names are not wishing to be disclosed.