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.
,
: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)
The tokens created by the activated ability will continue to have all creature types if Maskwood Nexus leaves the battlefield because those tokens have changeling. Other creatures you control will revert to their usual creature types unless another relevant effect is affecting them.