Quick Answer. The function of motor neurons is to release the neurotransmitter acetylcholine, which are released at a junction known as the neuromuscular junction, that bind to postsynaptic receptors, causing the muscle fiber to respond and result into a muscle movement.
The critical element that culturally sets humans apart from other species is the functional superiority of the human brain. That existing human culture has three axial components, namely politics, religion, and technology, which influence the affairs of mankind, must be obvious to all with a passing interest in human behaviour.
Humans share many traits with other apes, and those other apes (i.e., non-human apes) don't have unique features that set them apart from humans. Humans have some features that are uniquely our own, but so do gorillas, chimps, and the rest. Hominid evolution should not be read as a march to human-ness (even if it often appears that way from narratives of human evolution). Students should be aware that there is not a dichotomy between humans and apes. Humans are a kind of ape.