Why is it thematically significant that all the large door are locked and that the only door which Alice has a key for is too a small for her to fit through?

The locked large doors in "Alice's Adventures in Wonderland" symbolize barriers to growth and progress. The key to the small door represents a potential path to personal transformation, but the fact that it is too small for Alice to fit through suggests that she is not ready to undergo that change. This emphasizes the theme of self-discovery and the challenges of transitioning into new stages of life.