Fair points. The 2020 Scrum Guide introduces the terms "customer" and "user" once each, but both in a significant passage. The term "product" is also more clearly defined as an abstract term for different implementations.

The manifesto was written by (mostly) software developers and it's fair to say it is very much about developing software. Scrum, over the years has evolved into a framework for any kind of creative work, not just software.