Crumple can be pictured as a shape giving way. Something was holding itself open — a flat sheet of paper, the front of a car, a person standing up, a line of defenders — and then it is pressed, or it simply lets go. It folds in on itself and ends up smaller, bent, and covered in folds that run every way. Nothing is folded and nothing flies apart; the shape is just no longer being held.
Wiktionary derives crumple from Middle English crumplen, a repeating form of crumpen 'to curl up', from Old English crump 'bent, crooked' — crump plus -le. Bent again and again is exactly what a crushed shape looks like.
Wiktionary 把 crumple 追到中古英文 crumplen，是 crumpen（捲起來）的反覆形，再往前是古英文 crump（彎的、歪的），等於 crump + -le。一再地彎、一再地折，結果就是一個被擠成一團的形狀。
Wiktionary entry for crumple, supplied in this evidence packet (kaikki:3f6f69a190036ae4:756363734:25237)
Three branches
把東西擠成一團
這是核心畫面最直接的樣子：外力一壓，東西就往裡折，體積變小、形狀不見。
verb · B2
To press or crush something so that it becomes smaller, bent and covered in folds, or to be crushed in this way — used about paper and cloth, and also about metal that is crushed in a crash.
揉皺；壓擠變形
人整個垮下去
人站著、臉撐著，其實也是一個靠力氣維持的形狀；力氣一走，它就跟紙一樣往裡折。
verb · B2
If someone's body crumples, they drop to the ground in a loose, uncontrolled way, because their legs suddenly stop holding them up.
癱倒下去
抽象的東西撐不住
防線、計畫、論點都是靠力氣撐開的形狀，撐不住的時候，用的還是同一個往裡折的畫面。
verb · C1
If a team, a plan, or someone's resistance crumples, it suddenly stops holding and gives way, so it no longer works or fights back.
潰散；撐不住