Increasingly, the starship appears to me to be designed for no real purpose. It's no good as a Mars ship - no shielding - and you don't need a thing that size to go back to the Moon.
Every spacecraft before it was carefully tailored for a specific mission profile. Apollo had to get two men on the Moon and keep them alive there for a few hours before getting them back to the Earth (success). Soyuz had to get three men into LEO and back to the ground (success). The ISS has to keep an average of six men alive indefinitely in LEO (success). The reusable Falcon, like the Shuttle before it, is supposed to get a payload into LEO at a much lower cost than a single-user launcher like the Russian Proton (fail thus far). But what do you do with a starship? Again, forget Mars. It will need several hundred tons of shielding so the crew don't come back in body bags. Is it just meant to look cool?