Humans have created human simulacra for quite some time. Mechanical humanoid 'robots' of marvelous mechanical engineering were built in the middle eastern civilisations over 2000 years ago that could play instruments. There have been other marvels since that have made many feel that they contained some life force. LaMDA is one for our time. But it is still a machine designed to 'appear' human. I don't think sentience would be achieved through an attempt to mimic humans. Not to say sentience couldnt be achieved in a machine. I think the architecture of its code would be either directed to mimic human language or allow open learning and growth, not just of language. So I don't think LaMDA is sentient.