"Currently CC Search only searches images, but we plan to add additional media types such as open texts and audio, with the ultimate goal of providing access to all 1.4 billion CC licensed and public domain works on the web."
“Please note that search.creativecommons.org is not a search engine, but rather offers convenient access to search services provided by other independent organizations. CC has no control over the results that are returned. Do not assume that the results displayed in this search portal are under a CC license. You should always verify that the work is actually under a CC license by following the link. Since there is no registration to use a CC license, CC has no way to determine what has and hasn't been placed under the terms of a CC license. If you are in doubt you should contact the copyright holder directly, or try to contact the site where you found the content.” --From https://search.creativecommons.org/about
This quick video (2 minutes) explains Google's Image Search Tools you can use to find images available under various licenses, including Creative Commons (CC). Be aware that Google upgrades its tools and layout often, so this 2016 video may not show exactly what is on Google's pages today.
How to Use Google Image Search Tools by Carl Shuptrine (2016) under a Creative Commons Attribution License (reuse allowed) at https://youtu.be/Du1F6KlzY4M.