My point is that it cannot solve the problems a blockchain can. You could not build a digital currency on git.

Cryptocurrencies are just git + proof of work. Git, on its own, is a blockchain. Adding proof of work to a blockchain solves the timestamping problem, which allows you to use that blockchain as a currency (i.e. prevent double spends). Many times that property is useful (more than just in currencies, e.g. trading stocks), but not always, and it is not an essential property of a 'blockchain'.