Picture someone calling a group out one by one and standing them in a row so that you can look along the whole set in one go. What matters is not who is first but that the row is closed: these are the ones, they are in this order, and you can see all of them at once. Every use of line-up is that row. Sometimes the row is real people standing still; sometimes the row is on paper, and what is lined up are players, performers or programmes.
The noun is formed straight from the phrasal verb line up, 'to stand in a row' (the source entry records it as deverbal from line up). So the picture inside the word is the action that made it: people were lined up, and the result of that action became a thing you can name, announce and argue about.
這個名詞直接從動詞片語 line up（排成一排）變來的（來源條目寫 Deverbal from line up）。所以字裡面裝的就是那個動作本身：本來是「把人排成一排」，後來「排出來的這一組」變成一個可以講、可以公布、可以評價的東西。
Wiktionary 'line-up' (noun) entry supplied in this packet — etymology_text: 'Deverbal from line up.'; source_ref kaikki:3f6f69a190036ae4:1946361438:1770
From the picture
名單上排出來的一組人
同樣是一排人，只是這一排不用真的站出來，寫在名單或海報上就成立。看的人一樣是從頭掃到尾，重點一樣是「就是這些、就是這個順序」。所以會有 in the line-up（在裡面）和 left out of the line-up（沒被放進去）這種有裡外之分的說法。
noun · B2
The set of players a team will use in a particular game — both the written list and the group of players themselves.
出賽陣容
排好順序的一串節目
這一排裡放的不再是人，而是事情。畫面沒變：內容已經定了，順序也定了，你可以從頭看到尾。差別只在「排」的方向從空間換成時間——不是一個站在另一個旁邊，而是一個接在另一個後面。
noun · B2
A set of events, shows or programmes that have been arranged to happen one after another.
節目排程
noun · B2
A row of people arranged by the police in front of a witness, so that the witness can look at them all and say whether one of them is the person they saw.
指認排列