In Mario & Luigi: Superstar Saga in Woohoo Hooniversity a room can be found, in this room there are blocks stored in here and are being studied. These blocks are called the Blocks of Nostalgia, and are blocks from Mario's Past Adventures. Upon hitting these blocks you gain some information about them.

The first block you can find is a Paper Block said to be made of a soft material and is pretty sturdy. This confirms in the main Mario world, the events of the Paper Mario games did happen.

The second block is an Exclamation Block that is being studied by scientist who are trying to uncover the technology that cases it to vanish. This could imply blocks in the Mario World are some kind of technology.

The next block is Pixel Block, being described as appearing metallic, and being made of an unknown secret material from the Mushroom Kingdom. Aside from possibly further connecting to my question on whether or not Pixel Mario is literal, this also ties into Super Mario Bros. In a previous post I mentioned how the Toads were turned into blocks and how this is the first game's explanation for Power-Ups. But I also mentioned it only applied to the first game and all other blocks are naturally occurring, well this confirms it. But it also means they aren't literally naturally occurring, someone is making these blocks.

The final block is the Dino Block, this block is from Dinosaur Land and is described as being made of a special shiny material, and it is shock resistant.

With all this information this basically establishes in the lore the blocks in Mario do have different versions, each man-made and made of a different material. This is also a way to connect and confirm the canonicity of several games. Mario & Luigi, Paper Mario, Super Mario 64, and Super Mario Bros. 4 Super Mario World.