No it’s not. A blockchain is a Merkle tree whose canonical “master branch” is agreed upon by everyone and difficult or impossible to change (e.g. due to PoW or a similar mechanism).
A Git repository is a Merkle tree whose canonical “master branch” is agreed upon by everyone and difficult or impossible to change (because people want to collaborate on a project). If you try to rewrite history and people don’t agree with you, they would just fork the project and get on with their day.
a similar mechanism, like... a consensus mechanism? public key cryptography? some kind of content-based addressing? social convention and agreement on which fork to use?
is it easy for you to go edit historical commits in the linux repo?