人從船上下來
這一組就是核心畫面，主詞是走下來的那個人。
verb · B2
To get off a ship or an aircraft, and also a train or a bus, either at the end of a journey or at a stop along the way.
下船、下飛機
核心畫面
One way to hold this word: the moment the gangway goes down and people step off the ship onto solid ground. The journey by water is over, and everything and everyone that was inside the vessel now comes out of it. Whether you walk off yourself or the crew brings you and your boxes off, the picture is the same — out of the ship, onto the shore.
disembark 的畫面可以想成：舷梯放下來，人一個一個踩上陸地的那一刻。水上的這段路結束了。原本在船裡的人和東西…更多收起
disembark 的畫面可以想成：舷梯放下來，人一個一個踩上陸地的那一刻。水上的這段路結束了。原本在船裡的人和東西，現在都要出來。至於是自己走下來，還是船方把你和你的箱子送下來，畫面其實是同一個——從船裡出來，踏上岸。From the word’s history
The source gives disembark as dis- + embark: embark is going into the vessel, and dis- undoes it, so disembark is coming back out. The word tree behind embark shows en- (into) plus bark, a ship.
字源資料直接寫 disembark 是 dis- 加 embark。embark 是上船，dis- 把前面那個動作反過來，所以是下船。再往前看，embark 裡可以拆出 en-（進入）和 bark（船），也就是「進到船裡去」。這樣一來，disembark 的核心畫面就是字面本身：從船裡出來。
Wiktionary (kaikki extract, source_ref kaikki:3f6f69a190036ae4:637239378:34295): "From dis- + embark", with the etymology tree listing en- + bark for embark
Two branches
把人或貨送上岸
同一個「從船裡出來」的畫面，只是換人來做這個動作：不是你自己走下來，是船方把你或你的貨送下來。
verb · C1
To take people or goods off a ship and put them on shore.
把（人或貨）送上岸