Sexual differentiation in humans is split into many different pieces. There is chromosomal differentiation (at conception), hormonal differentiation (mostly through puberty), hormonal exposure in the womb (between 3-9 months), neurological differentiation (well into early adulthood in some cases).
Intersex conditions exist, and many go undetected until well into adolescence.
With all this, coming up with a consistent definition of male and female is actually pretty complicated, with lots of edge cases.
> Male/female have precise scientific terms that apply to all animal species.
Lookup how fruit flies are sexed, then compare to humans :) The animal kingdom can be a very different world.
