WHAT TYPES OF CONTENT CAN BE CC-LICENSED?
You can apply a CC license to anything protected by copyright that you own, with one important exception.
CC urges creators not to apply CC licenses to software. This is because there are many free and open-source software licenses which do that job better; they were built specifically as software licenses. For example, most open-source software licenses include provisions about distributing the software’s source code—but the CC licenses do not address this important aspect of sharing soft- ware.
Attribution (BY) Allows licensees to copy, distribute, display and perform the work and make derivative works and remixes based on it ONLY if they give the author or licensor attribution. Since version 2.0, all Creative Commons licenses require attribution to the creator and include the BY element.
The best practice for marking your work or for giving attribution is to follow the TASL approach. This applies to both your own portions of the content, as well as for the portions of the content created by others:
When providing attribution, the goal is to mark the work with full TASL information. When you don’t have some of the TASL information about a work, do the best you can and include as much detail as possible in the marking statement.
Note, that starting with Version 4.0 the licenses no longer require a reuser to include the title as part of the attribution statement. However, if the title is provided, then CC encourages you to include it when attributing the author.
Creative Commons licenses are only applicable where copyright protections would apply. If a work is in the public domain, then copyright does not apply, so a creative commons license cannot apply.
If an exception to copyright, like fair use or the educational exception applies, then a the terms of a creative commons license do not apply. When copyright doesn't apply to a work, then there are no rights for the CC License to control.
It is very important to carefully consider the options before deciding to use a CC license on a work. The licenses and CC0 are irrevocable. A CC license applies to a work until the copyright on the work expires. This safety feature assures reusers that the creator can’t arbitrarily pull back the rights granted them under the CC license.
Copyright ownership is another important consideration. Does the work only have one creator? Two? A team? A company? If the material was created within the scope of employment, the creator(s) may not be the holder of the rights and may need to get an employers permission before applying a CC license.
Creative Commons Licenses - Basic information flyer https://wiki.creativecommons.org/images/6/6d/6licenses-flat.pdf
https://creativecommons.org/2020/01/07/u-s-appellate-court-enforces-ccs-interpretation-of-noncommercial/ - As long as commercial actors are not acting independently for their own commercial gain but solely on behalf of noncommercial actors, they are protected by the license granted to the noncommercial actors.