Corpse Wiki & Guide

When you die, a corpse spawns at your death location holding every item you were carrying. Right-click it to reclaim your items; it disappears once emptied.

No — the corpse holds an infinite amount of items, cannot fall into the void or burn in lava, and floats in liquids, so your items stay safe even after a dangerous death.

After one hour the corpse turns into a skeleton to indicate it has existed for a while, but your items remain inside and retrievable.