The license footer on Wikidata lists explicitely the namespace whose content is CC0. EntitySchema should be added.
"All structured data from the main, property and lexeme namespaces is available under the Creative Commons CC0 License; text in the other namespaces is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy."
should be:
"All structured data from the main, Property, Lexeme, and EntitySchema namespaces is available under the Creative Commons CC0 License; text in the other namespaces is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy."
Code pointer: i18n message wikidata-copyright in the WikimediaMessages, see: https://github.com/wikimedia/mediawiki-extensions-WikimediaMessages/blob/ea4aff2bd0af6faaaa5b02bb303f873f8db60946/i18n/wikimedia/en.json