Blockchain is a terrific idea! Make it blockchain!! Not "block chain" like the git log but "blockchain" make all software use blockchain to make the world a better place for all of us!!!
Nope the git log is a merkle tree.
The blockchain is a merkle tree plus all the layers of overengineering you need to have a consensus algorithm. And usually you "need" a consensus algorithm mostly for ideological reasons. My view is that building trust is better than assuiming it can't or shouldn't exist.
To be pedantic, both git logs and blockchains are actually Merkle DAGs or Hash Graphs, whichever you prefer. All Merkle Trees are Merkle DAGs but not all Merkle DAGs are Merkle Trees.
Merkle tree is a technical term with a specific meaning.
Block chain is a fairly generic, badly misused term that I assert also covers the git log, which is actually a chain of cryptographic blocks where each block includes the hash of the previous. It even has a consensus algorithm. You can disagree, but your assertion is just an opinion in constrast to a misuse of the term Merkle tree.