That's because you're seeing them after literally thousands of years of evolution and simplification.

马, for example, is the simplified form of 馬, which is traceable back through the millenia to a pretty recognizable picture of a horse back around 1300 BCE or so. (http://en.wiktionary.org/wiki/%E9%A6%AC#Etymology)

Same with 女, which originally was a drawing of a stick-figure woman with breasts. (http://en.wiktionary.org/wiki/%E5%A5%B3#Etymology)