People say Herobrine is a dead miner. This common theory inspired me to create this theory.
Have you ever wondered why there are so many buildings in the Minecraft tutorial world? Well, my thought is that those are the stuff that Herobine made before he died. That unfinished house at the start of the tutorial might be the last building that "he" was going to make before he died. The strongholds and mineshafts could have also been made by "him". Herobrine might just be the ghost of that miner. What if every randomly generated building is not "randomly generated" and is actually one of Herobrine's creations?