You're free to use my assets and pack them into a bigger set but I would absolutely appreciate credit, and you cannot license them CC-BY 4.0 as mine are CC0 licensed. Meaning you can't put a more restrictive license on them. Thanks!
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Hey Kenney, I love your work, I’ve used it several times always with credit and I agree 100% that you should be credited. But a minor correction here, if you license your assets as CC0, other people are free to use them however they like, including repackaging them with any other license of their choosing, for free or for profit.