Do you think Animal Farm’s message would come across effectively to someone who knows nothing about Soviet history or the conflict between Stalin and Trotsky? What might such a reader make of the story?

This would be a very interesting essay. I think even if the reader were not familiar with the background of the story, it is still interesting. Human nature hasn't really changed all that much since Stalin so this story even works a modern parable. Greed, power, betrayal and brotherhood are still relevant .Clearly humans are personified through the animals and one would not have to look far to find similarities even in present times.