What is the oldest myth or legend which is known to mankind?
It's rather simple to determine the age of physical objects, be that pieces of everyday objects, but also written documents. These latter give us to some degree a view into the thoughts or beliefs of the people from the past (like the bible, like the Qumran Caves Scrolls, like the Kish Tablet), carbon-dating allows determining the age.
This is more difficult with spoken language. If they describe an event or a happening it can only be attributed to a certain time, when the event is detectable or known to have happened (like something geological, a big flood, an earthquake, use of lands now submerged, must have happened before a volcano errupted etc.). Within these limits that the myth can somewhat be time-attributed, what is the oldest myth or legend mankind knows?
(I'm aware of this old, but unanswered question. I believe this is similar difficult but not identical and can have an answer)