The only reason we know how Pizarro conquered the Inca is because he wrote it down. The bulk of what we know about Inca life comes from the Spanish who wrote it down. Most of the rest comes from archaeology and guesswork.

If you've got evidence that the Inca military had organized tactics, like units, feinting maneuvers, flanking attacks, procedures for taking fortified positions, covering fire, strategic retreat, breastworks, defense in depth, etc., I'm interested.

We do know the Inca had no plan for when their leader was captured but not killed. But Pizarro knew about that one, and that's how he defeated an empire. Disrupting the enemy's command and control is a well-understood technique in Western military tradition.