The book is at least a decade or two out of political fashion.
For thousands of years, certainly in European culture, the default human entity, when not specified, was masculine in gender. By which I mean grammatical gender, not the current politically vogue meaning of "gender."
We don't need to disregard thousands of years of knowledge because the authors were unaware of what would be PC in their future. That would be puerile. ("Childish," from the Latin word for "boy.")
The Latin word for boy is "puer": "a boy, lad (typically between ages 7-14 but could be younger) (older than an infans but younger than an adulescens)" - https://en.wiktionary.org/wiki/puer#Noun_4 .
Grammatic gender doesn't always match natural gender even in the European languages. "Wīfman" means "woman" in Old English but is grammatically masculine. The Old English "mann" meant generally "person". https://en.wiktionary.org/wiki/mann#Old_English making "wīfmann" a female person and "wæpnedmann" a male person, though "wer" was the usual word for "adult male" (remaining in "weregild" and "werewolf").
In modern Swedish there is no masculine gender, and "man" can mean either "an adult male" or "a person". Consider "Hysterektomi ... kan också göras om man har cellförändringar eller cancer i livmodern." which in English is "A hysterectomy can also be done if one has cell changes or cancer in the uterus." (from https://www.1177.se/behandling--hjalpmedel/operationer/opera... ).
The Swedish "man" in that sentence translates directly as "one" in English, not "adult male", though usually in English we would write "you" as a sort of third-person pronoun, over the more formal "one" - https://en.wikipedia.org/wiki/You#Third_person_usage , even when we don't know if the reader has a uterus.