One of the single worst lines you will ever hear in the context of a business environment is, “People are simple.”
That’s bunk. What motivates people can can be simplistic (think Maslow’s Hiearchy of Needs) but from that springs a font of applied complexity. Human beings operate at different levels of self-awareness (from blithe to zen master) and can hew to multiple, contradictory notions at the same without their heads exploding.
We are not logic machines. We are organic and squishy. The outputs seldom flow directly from the inputs without modification. Correctly identifying the latter is great, but don’t think the sum of those alone will always add up to the former.
Recognizing this helps prepare you for the interpersonal adventures of the average day, and makes you more likely to stand back and give a knotty issue or unfathomable personality the time and due care they require to be successfully untangled and dealt with.