The "ending" of minecraft is just the point at which you have access to the entire game. You probably know what The Nether is, that hellish looking place you a

The "ending" of minecraft is just the point at which you have access to the entire game. You probably know what The Nether is, that hellish looking place you access by making a portal. Reaching The Nether is progress, by getting there you get access to stuff you didn't have before, sure you can do whatever you feel like in Minecraft, but by getting there you can do more stuff than before because you have access to more stuff. By defeating the Ender Dragon you are free to roam The End (which is the name of the whole place) and thus you finally gain access to everything the game has to offer.