Although Graydon did begin playing around with ideas for a programming language in 2006, very little of that language survives beyond the general philosophy of "as fast as C++, but memory-safe and with modern features". There are enormous swaths of the language that are totally unrecognizable if you go back beyond 2012 or so (which is when I personally think "modern" Rust began to emerge). This is about when the borrow checker first appeared, which eventually became the core feature that much of the rest of the language came to be designed around. That said, it still took a lot of iterations on the borrow checker to arrive where we are today.