All languages back then, all of them, were "high-level" languages, including C. Look at the history of BCPL, B and C and how the goal was to write Unix in a "high-level" language. You can go hear Brian Kernighan himself tell you all about it.

C as a low-level language is revisionist history. Rust is a high-level language and yet it is a "lower level" language than Java. Same as C vs Pascal. You could write very low level code in Turbo Pascal back in the 80s, the demoscene used it a lot alongside assembly, it had inline assembly even.

EDIT: and to answer your question on what else was "low-level", Forth.