Someone who lives for exactly 365 years is obviously no longer alive afterwards, in other words dead. My guess is that "God took him" means he suffered from a mental disease such as Altzheimer - similar expressions are known in many languages.

Mythologies can be very specific about details, making us wonder about the underlying reality. For our topic, we probably have to acknowledge that the authors and early readers were convinced of the truth of their writing, by a notion of truth differing from both our notions of "literal reality" and "symbolic invention". Similarly, the notion of "existence" was different from ours. For a proof, consider the story of Elijah (1 Kings): the "existence" of Baal remains unquestioned (- after all, how could he have priests if he did not exist?), just his lack of power is taunted at.