Why are humans so predictable

for every human, there are physical attributes, emotional attributes and intellectual attributes just any other object excluding emotional attributes, however they are called as physical properties and chemical properties and so on other properties.

Now 2h2 + o2 –> 2h2o this nature since you learned, and when ever it repeats as a question, you would always say, the result of the what happens when hydrogen mixes with the oxygen.
Now just because you could tell it is water, do you claim that you have predicted the outcome?
so how the moral of the story is, define the question appropriate enough which disctincts the human nature and predictability( from your perspective).