User blog comment:Zathronas/Speculative Author - What's the deal with Salem?/@comment-27803627-20160217204410/@comment-24218038-20160218174421

Actually, again in V2 Ep4 They were celebrating the 80th anniversary of the end of the great war.

As for needing sentience to use dust, In world of Remnant: Dust, it's explained that anyone with an aura can use dust. It's also explained that animals have aura. technically they can use it too but you do need a certain level of intelligence to use dust.

There is one animal that seems to use it's semblance, Zwei.