The true statement about every public domain work is:
It is not protected by copyright or Creative Commons licenses.
This statement accurately reflects the nature of public domain works, which are free for anyone to use without restriction. While some public domain works may be older than 100 years, not all are (for example, works can enter the public domain because the copyright has expired, regardless of their age). Additionally, the merit of the work is subjective and not a defining characteristic of public domain status.