The tale that arrived from nowhere
The Thousand and One Nights is an old Arabic collection, assembled over centuries. Aladdin is not in the early manuscripts of it.
It appears first in French, in the early 1700s, in Antoine Galland's enormously popular translation. Galland recorded in his diary that he had heard it from a Syrian storyteller named Hanna Diyab, who was visiting Paris. No earlier Arabic written source has ever been found.
So one of the most famous stories in the world entered print through a conversation between two men in Paris, and everything since — every pantomime, every film — comes down through that.
What the original actually contains
The differences are not small.
There are two spirits, not one: one bound to a ring and one to the lamp, and the ring's is the weaker of the two. There is no limit of three wishes — that rule was invented much later. There is no carpet; flying carpets belong to other tales in the collection.
The villain is a magician from the far west of the Islamic world, not a royal adviser. The princess has a name of her own. The story is set, in Galland's text, in China.
And Aladdin himself begins the story as a thoroughly idle boy who will not learn his father's trade. He is handed a fortune he did nothing to deserve, and the rest of the tale is him slowly becoming somebody capable of keeping it — learning what things cost, how to speak to people, how not to be cheated. That arc is the whole point of him, and it is usually the first thing an adaptation cuts.
Reading it now
A story this old, carried this far, has been retold by a great many people with a great many motives, and some of those retellings lean on tired ideas about the places they are set in.
Our version stays with what the old tale actually does: a boy with nothing, a piece of enormous luck, and the long unglamorous business of becoming worth it. We have kept the magician a magician, left the invented names out, and not borrowed a single thing from the films.