To try and answer this academically, if you choose to believe G-d wanted to destroy these people, than no proof can sway you. I will though, give my opinion. I would like to compare this to the conquering of the American Indians, who as you will note did not practice such human sacrifice.
They worshiped vague beings of sorts and many tribes had various different rituals. Yet, upon the coming of the English, they too were subjected to Small Pox, which wiped out a tremendous amount of their population, just as it did with the Aztecs. Additionally, the Spanish had lots of help from the local kingdoms and tribes, who all felt they would benefit from the collapse of the Aztec's, so they army grew to quite a formidable size.
Additionally, one must keep in mind that the weaponry, as well as tactics, of the Spanish were light-years ahead of the tough rock weapons and basic war charges that dominated the Aztec and local military. So the factors are there to explain how this happened, although like I said, if one wants to believe that there was divine intervention (which you are entitled to believe) than there is little anybody could do to dissuade you. Interesting question!
P. S A great book, (historical fiction) which goes through the life of an Aztec citizen as he rises in the rank and travels around South America, is "Aztec." It's about 1000 pages long though, so you better want to read it!
-EDIT- Also, just to throw in there, it is important to realize that the Aztec's were at a weakening in their kingdom. Several allies had broken off and there were plenty of political issues plaguing the empire at the time. To say they would still be going to this time is doubtful.
They likely would not have made it a a few more decades, more or less survived the rapid change during the 19th and 20th centuries. Just as the Mayans had collapsed multiple times, they likely would have fallen as some point in the future.
Spain was not a pretty place to live in the medieval ages. They were United and strong, but they were really impoverished and the conquistadores that conquered the South American Empires all had backgrounds from poor areas. If you were poor and had no formal education, you really had no choice but to fight them.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.