How long did the last fully reusable superheavy lift rocket take to develop? There's never been one you say? Right. So you have no metric for measurement. The closest equivalent: SLS is flying hardware who's design originated in the 60s, and Blue Origin began development 24 years ago.
Starship is developing at light speed by comparison to anything approaching it's size.
Still think it's happening slowly? Feel free to build one yourself in less time. I'll wait.