The space shuttle was aerodynamic for a very specific reason - they had to do a mission (that never happened) where they would launch, deploy a spy satellite into a specific polar orbit, and return back to Vandenberg Air Force Base in California in a single orbit. The result was a requirement for a lot of cross range, which needed large wings that hurt its performance a spacecraft.

Starship doesn't have that - and so it can be much more optimized for it's purpose. It's basically tanks with a cargo bay and control surfaces, while the shuttle had to toss it's tanks away every flight.