Hello, I would suggest you focus on releasing paid packs each with a free content demo. Just like I do. This way the audience gets to try out your pack and if the style suits their project there is a chance for them to buy the premium version of the game. I also think this is smart because once they claim the free pack, you can release updates and that will continue boosting your presence.
I would occasionally release some free stuff and post it on social media but as you mentioned in the post above, too much promotion leads to people ignoring or people start using your assets in games that are known as asset flips making the art seem like its low quality even if it is not (this is my opinion).
I also read your license! Hehe. I love the axolotl. Not relevant but I have a project focused on axolotls but its on hold since I got quite busy with life.
I hope I helped :)
Good luck my friend,
Admurin