With the right hardware combinations, the only break you'd theoretically have in the System/MacOS/macOS history from 1984's System 1 to 2023's macOS Sonoma 14.1 is from MacOS 9 to MacOS X 10.0. OS X was actually a completely new operating system and oftentimes you had both OSes side-by-side on the same disk to either dual boot or to run OS 9 stuff in Classic mode under OS X.

(With full disk encryption, T2 chips and other various low-level hardware changes this might not actually be feasible under Apple Silicon chips, but at least through the Intel days you could have upgraded a system with hardware changes in the same way.)