With extreme effort, Starship will eventually take reusability to ~100%. There are many tough issues to solve with this vehicle, but the biggest remaining problem is making a reusable orbital return heat shield, which has never been done before. The Shuttle’s heat shield required over 6 months of refurbishment by a large team, so was not reusable by any reasonable definition of the word.
This will take a few kicks at the can to solve and requires building an entirely new supply chain for low-cost, high-volume and yet high-reliability heat shield tiles, but it can be done.
This is why we started from day 1 thinking hard about rapidly reusable heat shields. It’s metallic, ductile, and the surface temperature is tailorable and controllable well below material limits. It certainly hasn’t been to space (or back) yet, but to the best ability on earth we’ve tested it to the full heat load expected during reentry profiles.