They cannot fling things to orbit, they can fling things very fast but a (smaller) rocket is still needed to finish getting to orbit.
and G Forces are extreme so this is only suitable for payloads that don't mind extreme G forces.
On reentry from orbit vehicles are going mach ~25.
The drag and resulting heat production at sea level would not be as easy to deal with if you were zipping along at Mach 25 right after launch. Even supersonic aircraft don't run full speed (for a whole host of reasons) at sea level.
Anyway, the earliest patent I could find was a steam centripetal launcher in 1918. It never went anywhere and it has been followed by a number of improbable reinventions that all faded away.
NASA and the US Army tried again in 1982 and thought they could put a 60g projectile down range at 3 km/s. Mach 8. Guns and rockets could perform as well or better with simpler systems and the idea was shelved.
https://patents.google.com/patent/US1332992 https://ui.adsabs.harvard.edu/abs/1982ITM....18..209F/abstra...