Most of the innovative parts of bitcoin have been done independently as pieces; it's novelty is the combination of things like Proof of Work (Hashcash, Bitgold)

Most of the innovative parts of bitcoin have been done independently as pieces; it's novelty is the combination of things like Proof of Work (Hashcash, Bitgold) with p2p consensus and asymmetric cryptography. Nothing special about its structure or operation inherently.