I'm saying that the package becomes yours when you download it. The package itself is unlicensed and free for everyone to use.
Viewing post in Optimized - Mushroom Pack comments
Your words look like public domain (CC0 https://creativecommons.org/about/cclicenses/)...
If I am right,
you should add the license into metadata for the asset pack(s):
"Edit asset pack->Metadata->Release Info->License for assets" It will increase the size of audience that will be able to find your art
If you want always be credited so yes you need CC-BY. If you want always be credited and don't want allow to change the license for derivatives you need CC-BY-SA. If you want to allow people to do whatever they want with it (even without any credits) so you need CC0...
You can even decide not to set license in metadata (return it to the initial value) and just write in text what you allow to do with your asset.... But if you want to know my opinion, it is slightly simple for CC-BY but it is also normal and everything is up to you
P.S As I see you are creating simple models... I can recommend you to create some low-poly keys or furniture for games such chests, chairs, tables...