Short answers, pulled from the story.
Euhemerus was most likely born in Sicilian Messene, though ancient writers like Diodorus Siculus and Plutarch suggested origins in Chios or Tegea instead. He lived during the late fourth century BC when Greek city-states were being reshaped by Macedonian power.
No complete copy of Euhemerus' main work survives today because only scattered fragments preserved within other ancient texts remain. These fragments appear in books five and six of Diodorus Siculus history, quotes from Eusebius Praeparatio evangelica, and references in Lactantius Divine Institutes.
Euhemerus claimed to have traveled to an invented island called Panchaea where he found inscriptions on a golden pillar listing births and deaths of deities as historical figures. He argued that gods began as human kings, heroes, or benefactors whose stories grew exaggerated over time rather than existing as supernatural beings.
Euhemerus served as the court's leading mythographer for Cassander who ruled from 305 to 297 BC during the late fourth century BC. This connection placed him at the heart of Macedonian political circles where Cassander likely commissioned his travels to form the basis of his famous work.
Modern academic literature defines euhemerism as the theory that myths are distorted accounts of real historical events treated universally across all myths. Earlier thinkers like Xenophanes Herodotus and Ephorus had already attempted rational interpretations but Euhemerus distinguished himself by applying this method to treat mythology as history disguised within layers of retelling.