In 1.13 you can create datapacks. Datapacks are basically very simple mods the user doesn't need to install. They can add/edit crafting recipes, add advancements, add functions, add structures, edit loot tables and do some more things. This is great, but editing them is really tedious. Here is a screenshot of me editing the loot table of a cow so it drops more beef:
I was creating a datapack for my survival world, and I had an idea. What if it were easier to edit. That is why I came up with this idea.
There should be an in-game datapack editor.
On the start menu, there is a button that says "datapacks". Click on it, and you get this screen
In this, you can select a pack and edit it with a simple drag and drop interface. I don't have enough time to create those things in photoshop, but it would be something like this
To download the other ones you need to make a folder in the versions folder for minecraft and put the client and JSON file for the versions in there. They all need to be named the same aside from file extensions. Once you do that, you will be able to choose that version when making a new profile with the minecraft launcher.