These days, most manual of styles everywhere frown upon usage of "man" to mean "human", but you have to remember that contributors to this course are not English native speakers – they simply didn't yet get the memo. ;-)
Please report, this should definitely not be the default translation.
naah, it's not the case. in Polish you often say 'człowiek' meaning 'a man,' cos saying 'mężczyzna' would be strange-ish, it would put some emphasis on his sex, which you didn't need at all.
you don't call a man 'a human' in a common English sentence, so no, the default translation should not be changed