User blog comment:SsVivid/What I Learned From Heart of Stone/@comment-5008504-20141207035213/@comment-1962440-20141209035258

Fully sentient automatons have been made in the past, this isn't a new achievement, just one that has only recently been rediscovered. I think we're looking at two separate concepts for "life" in this regard, this is the only way I can understand the discrepancies.

Life in regards to sentience isn't impossible to create, this seems to be relatively easy, with the right knowledge and resources available. There is evidence this was done as far back as Senliten's time of the second age, which was very early on.

Life in regards to generating anima isn't possible to create, only Elder Gods can do it from nothing. Zaros had to take living things and modify them into something completely different for it to work.