This mod allows adding new Blocks and items.
Its not called simple cause its simple to use,
its called simple because its code is as simple
as possible.
Put jsons with the same structure as
src/main/resources/data/simple_creator/items/test_item.json
src/main/resources/data/simple_creator/blocks/test_block.json
in a (newly introduced) global datapack (minecraft root)/datapacks.
This datapack needs a pack.mcmeta.
After a restart, the so created items are available ingame.