To quote, "if the human brain were so simple that we could understand it, we would be so simple that we couldn’t".

So…

> this is the part where somebody stumbles in to say "dOn'T hUmAnS dO ThE sAmE tHiNg????"

…yes, but also no.

Humans will always seem mysterious to other humans, because we're too complex to be modelled by each other. Basic set of behaviours or not.

> "if the human brain were so simple that we could understand it, we would be so simple that we couldn’t".

https://www.lightspeedmagazine.com/fiction/exhalation/

Perhaps there is some definition of ‘understand’ where that quote is true but it is possible to understand some things without understanding everything.