Yaro, this is a great post! Personally, I have banners and other advertising avenues. I am surprised though that you don’t mention Adsense as it fulfills all your criteria: It is easy to set up, it is totally automated and you don’t need to do anything and it is totally passive. It will perhaps be of no use to you, but to beginners, I think it should be a good option, don’t you think?
If you have a knack for creating unique images, there’s no need to fuss over your own inventory. If your creations can be easily printed onto a product, then you can make money. Upload your designs on a variety of websites like CafePress. If someone likes them, the company prints them up and ships the product. You could create unique designs for calendars, books, T-shirts, bags, hats, greeting cards, or posters and get a commission for each one sold. Some of these sites include Zazzle, Teespring and Lulu.
How much will you make? I think my best month with Google AdSense was almost $5,000 over the last ten years. That amazing month blew my mind since it was actually near the beginning of my blogging journey. When you go from making zero to $5,000 in a month, that will rock your world. For me, it also got me even more excited because I knew there were other ways to monetize.