Git was built specifically to avoid the necessity to have one authoritative server.

https://git-scm.com/book/en/v2/Distributed-Git-Distributed-Workflows

In contrast with Centralized Version Control Systems (CVCSs), the distributed nature of Git allows you to be far more flexible in how developers collaborate on projects. In centralized systems, every developer is a node working more or less equally with a central hub. In Git, however, every developer is potentially both a node and a hub; that is, every developer can both contribute code to other repositories and maintain a public repository on which others can base their work and which they can contribute to.

That is patently false. It was developed to help develop the Linux kernel, which famously has multiple decentralized repositories managed by different maintainers.

The fact that most companies use it in a way you describe, with only one central repository, does not mean that git is not distributed.

I agree it's not a blockchain, (although it has chain properties) but it is kinda decentralized. By convention projects almost exclusively have a single remote, and by convention that single remote is treated as an ultimate source-of-truth... But you can absolutely have the same repo with multiple remotes defined, and one could establish different schemes to determine which branches on which remotes represent what in terms of "truth".

Counterpoint: it is a chain and there absolutely is not one server.