Kudos to all those below who have scholarly contributions regarding the details and lyrics of the song Barbra Ann.
I can only speak to the music. Recently I heard an interpretation of the song in a solo cello encore. Clearly 90% of the audiene did not recognize the tune. What was emphasized was the breathing of the tune in and out in pitch and phrase. The respiratory quality of the tune is so human it rivals Motzart's depiction of tears. No wonder it has been a hit since 1666.