What aspect of this “has never been done before”? Its a multi-stage rocket (NASA and the Soviets have been doing that for about seventy-ish years and the Nazi scientists we all recruited were doing it for even longer). The main innovations are material choice (which is debatable) and landing a rocket on a pad, which is mostly a function of having good computers.
Space flight is hard. That said, there is a very strong argument for being much less iterative. Especially when the quest for a reusable rocket involves constant spraying of wreckage across oceans and land.