The writer uses these questions to emphasize that all people will die. Alternate translation: "No one can live forever or bring himself back to life after dying" (See: [[rc://en/ta/man/translate/figs-rquestion]])
Here "hand" refers to power. The writer speaks of Sheol as if it were a person who has power over those who die. Possible meanings are 1) a person cannot bring himself back to life after dying or 2) a person cannot keep himself from dying. (See: [[rc://en/ta/man/translate/figs-metonymy]] and [[rc://en/ta/man/translate/figs-personification]])