> Imagine if git was lost and it had to be recreated, would it make sense to rebuild it exactly as it is now?

I find your argument to be "if things were different, wouldn't they be different?" which I don't find to be of much substance... but let me fancy your thought experiment:

Assuming the remembrance of the features/API was not lost there would be a worldwide effort to recreate it as soon as humanly possible due to the problems it solves better than any other SCM on the market. It's critical for global software engineering productivity. I have no doubt that a similar (if not exact copy) of git would be produced in very short time.

Let's take another piece of Torvald's software and ask the same question: if Linux disappeared overnight would things be done different? Well, yes... sure. but would things also be re-created near 1:1 due to the known success of the Kernel? Also yes, and as fast as humanly possible.