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Another option is to look for assets from people here on itch or other places where you can download stuff directly from creators. It only involves a little extra work (i.e. importing the assets into your project manually instead of letting the store do it for you) and you will be able to find more unique works. You'll also be supporting indie artists by hopefully crediting them and/or paying. 

I do that all the time also Unity make it easy to import assets from outside the store however when purchase from the unity assets store you gain a license for using the asset does Itch.io have something similar?

Yes, but it is up to the uploader to write the license terms, usually included with the download in license.txt or similar