"chain of digital signatures" was referring to the method of assigning value between owners via transactions (s2). That's not the blockchain, nor was it a new

"chain of digital signatures" was referring to the method of assigning value between owners via transactions (s2). That's not the blockchain, nor was it a new concept -- see bmoney, Wei Dai, 1998. They described the blockchain as an "ongoing chain of hash-based proof-of-work, forming a record that cannot be changed without redoing the proof-of-work"