How we cite our quotes:
On the lower deck in the babel of two hundred voices he would forget himself, and beforehand live in his mind the sea-life of light literature. He saw himself saving people from sinking ships, cutting away masts in a hurricane [...] (1.5)
Ah, to be young and full of dreams. Of course these dreams are a sign of an overactive imagination, which emphasizes Jim's youthful, if a bit foolish qualities.
He sighed with content, with regret as well at having to part from that serenity which fostered the adventurous freedom of his thoughts. He was a little sleepy too, and felt a pleasurable langour running through every limb as though all the blood in his body had turned to warm milk. (3.5)
In this scene, Jim seems like a small child. He's sleepy, tired, and ready for some good dreams. The adventurous freedom of his thoughts will soon be squashed when his mind becomes dominated by the Patna scandal. So much for serenity.
"Were I to go home tomorrow, I bet that before two days passed over my head some sunburnt young chief mate would overtake me [...] and a fresh deep voice speaking above my hat would ask: 'Don't you remember me, sir? Why! little So-and-so. Such and such a ship. It was my first voyage.' And I would remember a bewildered little shaver, no higher than the back of this chair [...]" (5.10)
Marlow has a whole lot of proteges, and Jim is by no means the first. Does that change your view of little Jimmy in any way? Does it make him any less special? If anything, Marlow's mention of all these young sailors he has met over the years emphasizes just how old he is.