You can now upload distinct product thumbnails from the product edit page:
These will show up on customer libraries (web and mobile), Gumroad Discover, and–most important–your profile. Finally, you can have a cover that sells your product effectively and have a thumbnail that represents it well in a browsing context. Yay!
They'll look better, and they'll make pages load a lot faster too–since having 9 full-size product covers load per page can be quite taxing.
Soon we'll be redesigning our products dashboard to bring these thumbnails there too. And add thumbnails to your product files so each file can have its own visual representation. Here's a sneak peek: