I think this sudden need happened too quickly for Itch to set up means to make the page look more presentable. It would take time to build or I guess partly import certain aspects like a tag / filter function at this time. There is a small notice on the download page saying, "We will be updating this page soon, we know it's difficult to navigate so many games. We know you want a button to add show everything in your library. No need to reach out. Any new games added to the bundle will automatically show up here. Thanks!"
Oh wait that's new. . . it didn't mention that they are working on a button. The client / app however doesn't sort based on genre / tags tho.