Git is somewhat similar to blockchains, but the similarity is very loose. Bitcoin has a shared state and enforces strict rules of how it can updated. For example I can't spend non-existing funds in Bitcoin. Also all state transitions are checked by all full nodes in Bitcoin.

This is different to Git that allows to perform any changes to text files without imposing any restrictions or checks on what changes can be performed. The ability to have a shared, verifiable state that can only be changed according to predefined rules, can be checked by anyone, and, theoretically, cannot be censored is the main selling point of public blockchain based systems like Bitcoin and Ethereum.

The main question is how much of that do we really need in practice to solve actual, real-world problems.