Caimarusa was published in a songbook by the Girl Guides of the UK. It was called "Musical Fun with the Brownie Pack." Unfortunately, this book has been out of print for quite a few years.

According to this book, the singing game is from Colombia. The story is as Sheila says: that after a long absence from her village the much-loved Caimarusa returned, and in her honour the villagers performed this dance.

It's possible that the UK Girl Guides could tell you something about the copyright, since they published it in a book.