Is The "Conquista" we Know True?

I have always read about the Spanish conquistadores and how they "conquered " the New World, and I have always had serious doubts about this, and now with the internet confirming that many things we took for granted might not be so true after all my doubts are re-doubled.

For example is it plausible that Cortes and a few hundred Spaniards and a few Indian allies was able to subdue thousands of well trained soldiers from a warrior empire and killed their emperor or whatever he was called and just took over everything? And the same thing happened over all of what is Latin America most of all with the Inca empire.

I have read testimonies of a man who saw 80,000 people sacrificed by the Aztecs to celebrate some God's holy day in 4 four days, can you see the logistical nightmare this would have been? Just for starters how do you keep 80,000 prisoners from revolting when they know they are going to a certain death?

Then in South America they just went in and kidnapped the emperor and with this they took control of a whole continent. Now I can tell you this history is a lie because there were also more primitive tribes which exist to this day which they couldn't subdue. So I think this whole thing is a lie.

I have read that Tenochtitlan the Aztec capital, full of wonderful temples and other buildings, causeways, land filled areas and other engineering marvels was just built less than two hundred years before the Spaniards came, and yet all of this marvelous engineers just disappeared when these guys showed up.

I think what happened is that these empires had come and gone a long time before the Spaniards got here and all they found was the remnants of these empires, people who had gone back to a more primitive lifestyle and who posed no problems to the conquering aims of the Europeans. But it was just so much more heroic to say a whole civilization had to be wiped out through cunning and courage before they were able to conquer this continent.