I've been wanting to ask this for quite a while:
How did Lyra even get so obsessed with anthropomorphism?
That's a good question.
Speaking of which, what was the first episode that had her sitting in that odd position?
you literally answered the question
that is where it began, because she sat like a human. I don't recall where the hands-part began, but "Sitting Lyra" is where it all started.
also, Sitting Lyra was first spotted in
Dragonshy.