Hmm. It appears that you clicked on the mod file, possibly curious what's going on. So I will explain the joke.
Yes, the mod is for Minecraft Forge 1.4.7. Hoppers don't exist in this version, and were added in the next update. So it's not an "item transport" mod because it adds a block that helps you transport items, it's actually transporting an item from one version to another. (Maybe, indeed, you are the item, and are being transported backwards alongside the hopper...... 🤔)
I documented just about everything I learned writing this mod into this document, including a short introduction to the tooling (using "voldeloom", a cursed version of Fabric Loom that builds old Forge mods instead), and how to get started using the API of the time and writing simple content mods.
Things went surprisingly smoothly (wasn't smooth, but wasn't the horrible abomination I was thinking it would be) and I had a blast doing this, I hope to do it again some time.