I'm speechless, Jack. So many tunes with similar melodies from so many different countries.
And I will never forget the first time I heard Smetana's Vltava (Moldau) in a music class in high school. To me it is the perfect example of how music reflects life. Even just the gentle musical representation of the water and waves at the beginning before the melody starts.
[Off topic, but similar to the concept of that article, have you read this Mudcat thread about the spread of a song across at least half of the land now known as Australia by our First Nations people, before any modern music recording technology?