Why did Connell make Rainsford an American and Zaroff a Cossack? Is there a political message to this story?

Richard Connell was an American author. The protagonist, during the time it was written, naturally had to be an American. This is an escape adventure story so a perfect American hero is needed for an American audience. He also needed an antagonist that was exotic and strange. Zaroff the Cossack seemed to fit the bill.

Should we make anything of Rainsford’s initial interest in Zaroff? Are the two men similar?