Nietzsche's Human, All Too Human begins with thoughts concerning metaphysics, called "On First and Last Things," its title suggesting issues about causality and teliology. This chapter also introduces issues about lack of human contentment and issues about language and expression.
The second section is "On the History of Moral Feelings," which title anticipates Nietzsche's arguments against religion-based morality (or traditional ethics wholesale). This section constructs a narrative about ethics in a philosophical system with no higher natural law, namely the extant ethic, one based in precedent and aggregate beliefs. That is, that things are right and wrong based on what lots of people have believed for some time.
After that is "From the Soul of Artists and Writers." Although it sounds poetic and artistically inspired, this section primarily denounces the notion that art and literature are divinely inspired. He maintains that commitment and continued work leads to great art, not artistic genius or any such inspiration. Notably, his ex-friend, Wagner, maintained the opposite in his writings. "Signs of Higher and Lower Culture," extends these arguments to apply to social hierarchies. He argues against Darwin explicitly here.
"Man in Society and Women and Child," is also anti-Darwinian and contains aphorisims about gender and family and their evolution. This is similar to the next section, "Man Alone with Himself," which applies metaphysical principles to man's existence and search for meaning. A poignant, poetic section, this portion deals with the difficulties that come with being alive and aware, and contains interesting arguments against Kant, through a philosphical system which Nietzsche calls, "obscurantism."
All in all, the work seeks to explain facets of human life in light of Nietzsche's atheistic and skeptical philosophy. It adds a fuller-bodied explanation to questions of life and its value in the aphoristic style of late-19th century German philosophy.