Correct, mouse. One of the big mistakes the early Darwinians (Huxley, Haeckel, et al.) made was this image of natural selection as something active. It's not; natural selection just means that some organisms have more offspring than others, and some (most, in fact) have no offspring at all because they die before they can reproduce, are simply sterile, or can't attract a mate. The last, sexual selection, is the only one with a sentient force ultimately behind it, namely the opposite sex.
Relative to chimpanzees, humans do have large penises: Twice as large, in fact. But more important in our evolutionary history would be opposable thumbs (found in all primates, so it first became prominent in the Eocene), bipedalism (found at least occasionally in all primates; habitual bipedalism first became prominent in the Lower Pliocene), and larger brains (Middle Pleistocene).
After the radiation of humans from eastern Africa from the Middle Pleistocene to the recent era, various traits were preferred by various populations. For example, I have flared nostrils, which would be an advantage in a hot, humid environment. As would my larger ears and longer limbs. Now, place me in Siberia with about the same technology as the Chukchi at the time of Russian contact, and I freeze to death rather quickly. Similarly, certain traits were preferred by sexual selection after the aforementioned radiation, hence (for example) the small breasts on Japanese women.