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
You can leave a comment here to support my proposal about making metadata visible for those who are interested in it https://itch.io/t/2919128/metadata-encouragement#post-7952450
Sentence from the description: "Please do not redistribute/resell" looks like a request, not a command. But If you are considering it like command... CC0 - public domain so everyone can redistribute and even resell...
I hope it is really CC0 because I am going to use it in mini jam 134