The Chariot is the card that most clearly betrays where the trump sequence came from. A triumphal chariot is not a random image: it is the central device of the Roman triumph as the Italian Renaissance imagined it, and above all of Petrarch's Trionfi, a poem in which Love is conquered by Chastity, Chastity by Death, Death by Fame, Fame by Time, and Time by Eternity, each victor riding in procession over the last.
That structure, a series of allegorical figures each defeating the one before, is exactly the structure of a trump sequence, and the word for the cards in the earliest records, carte da trionfi, is the same word. The tarot trumps are not identical to Petrarch's six, and no direct derivation has been demonstrated, so the relationship is best stated as a shared visual and literary culture rather than a source. But it explains why the trumps are ordered and hierarchical at all, which no Egyptian or Kabbalistic theory does.
It also explains why the order varied. Fifteenth-century Italian cities did not agree on the sequence, and scholarship distinguishes several regional orderings that differ over where the virtues and the celestial cards sit. There was no canonical order to be encoded, because there was no single order. Any reading of the Major Arcana as a fixed journey with fixed stations is working from a sequence that was standardised comparatively late, largely through the French pattern, and is treating a printer's convention as revelation. That does not make the journey reading useless, it is a genuinely productive way to work with the cards, but it makes it a modern interpretive achievement rather than a recovered secret.