The native peoples of America could have successfully defended their civilizations if they had been more suspicious of the Spanish to arrive?

Answer 1

The native people of America were mostly in early stone age industrial development. Means there were very few of them and extremely poorly equipped. In South America the level of development was a bit better- but still not even approaching the level of the Trojan war (early Bronze Age). Moreover most of the tribes were at war with each other- with the Incas and the Aztecs being the most recent (and mercilless) conquerors