The Fire Nation in the world of Avatar being held in the same regard as Caucasians/Modern Europeans is…incorrect.
I can see how people can see that due to them being the poster child for world domination but when you dig deeper into real history you learn that Greeks, Romans and even some early Europeans were actually of indigenous decent.
Yes Indo-Europeans are nothing more than light skinned black folks. But as time went on and things became even more corrupt even those people got conquered by those we now refer to as white folks. Even the term “Indo-European” is a modern term given by modern white folks to apply to an ancient people to give them some sort of standing in the ancient world.
So no the fire nation (at least not based on what I’ve been presented) do they apply to white people.
To even apply them to people of the fire nation with their indigenous symbols and ancient culture is the same as saying that white people are as old as the indigenous people on the planet and that — is a lie Maury.