Artifact
Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.

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: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)
The subtype Shapeshifter that appears on the type line is mostly there to reinforce the flavor. A creature card with changeling is just as much an Elf, a Dwarf, a Sliver, a Goat, a Coward, and a Zombie as it is a Shapeshifter.