re: Avengers Thanos Storyline Continuity Question - MAJOR SPOILERS

It's actually pretty easy to explain. The clues are all there.

The Asgardians teach their youth certain things as fables, but more importantly as warnings.

It stands to reason that both Bor and Odin knew the terrible danger anyone with the full power of the Infinity Gauntlet would pose to all of the realms so they constructed a replica as a "teaching aid"

Also, Asgardians clearly do not have a high opinion of the Kree or those associated with them.

Here are the three major clues if you're paying attention:

Thor: The Dark World - Bor never told his son that the Aethir never left Svartelfheim.

Agents of Shield episode "Who you really are" - The disdain, if not outright disgust in Sif's voice when she's speaking with Val-Tak (she never uses his name, just calls him "Kree" in a mocking, disrespectful tone)

Age of Ultron - How could Thor possibly know that FOUR Infinity Stones were revealed (including the one from Guardians of the Galaxy) unless Asgard received that information from the Collector or the Nova Corps.

So we know that the following stones are out there:

Mind (Yellow: Loki's Staff - Vision)
Space (Blue: Tesseract)
Reality (Red: Aethir)
Power (Purple: Orb on Xandar)

That leaves the Soul and Time Stones (Green and Orange)

Key owners of each in the comics:

Soul - Adam Warlock, Doctor Strange
Time - Thor, Gamora

The reason I've put those names in bold is because the soul stone will likely be introduced in Doctor Strange (Eye of Agamotto perhaps?) and the time stone will likely be used by Thor to reverse Ragnarok in the next film (which is why it's being called a "game-changer")