It was created none other than the creator of bitcoin, Satoshi Nakamoto. In my own opinion it was created to avoid middlemen, to give the freedom on keeping your own record by your won. Since computer will not require money and will cost anything on doing thw tasks that any middlemen do, blockchain is the solution created by Satoshi.
Basically, it seems to be patented to Satoshi Nakamoto, but satoshi could probably not created blockchain without any sources from other people. So it is probably invented right before satoshi release bitcoin, because blockchain hasn't yet having a working project where it could be reflected into until bitcoin's release.
Actually, no one knows who totally build or created that Blockchain technology and upon searching for the people who created it I found out that the creator of bitcoin was also the creator of blockchain which is Satoshi Nakamoto. But, we do not know if Satoshi Nakamoto is a single person or a group of people and until right now no one really knows who is the real Satoshi Nakamoto.
Like @plvbob0070 said, No one actually knew the origin creators of blockchain technology. But if there's one thing we know is that, the first blockchain powered cryptocurrency is Bitcoin which was originally created by a man called Satoshi Nakamoto. Bitcoin was the first real implementation of Blockchain technology.
The creator of blockchain is commonly known was Satoshi Nakamoto and the creator of Bitcoin. The creation of blockchain of its purpose was to have a public ledger for Bitcoin. Until now, there's no clarified identity to Satoshi Nakamoto.