Is the story of Samson killing a thousand men (Judges 15:15) with the jawbone of a donkey supposed to be taken literally or is it an allegory or metaphor? Seems unlikely in the extreme that a man could kill one thousand men with the jawbone of a donkey which is neither sharp nor heavy.
The verses there say that וַתִּצְלַ֨ח עָלָ֜יו ר֣וּחַ היָ֗ - the spirit of G-d came over him... The whole story was clearly miraculous. It says something like this, by the way, for each of Samson's fights: the Bible never says that he was "strong".
So if a man can defeat a thousand, also impossible, I don't see the problem with him using a donkey jawbone to do it. The whole thing was beyond the normal rules.
When we want to question the possibility that something might not be literal than we must understand the context.
For Example if I was discussing the Story of Purim and I said that the Jews killed 75,000 people. I would not question that number as not being literal. For I know that Story and how vast the Kingdom of Achasverosh was and the decree of a mass killing of all Jews from all his empire and then, things got flipped and the Jews were able to fight those enemies. 75,000 sounds like a fair number for the story at hand.
We study the story of Samson and we see many odd things that normal men cannot do.
וַתִּצְלַ֨ח עָלָ֜יו ר֣וּחַ יְהֹוָ֗ה וַֽיְשַׁסְּעֵ֙הוּ֙ כְּשַׁסַּ֣ע הַגְּדִ֔י וּמְא֖וּמָה - And the spirit of the Lord came mightily upon him, and he ripped apart (the Male Lions) as one would have ripped apart a kid (baby goat).
וַיַּ֥ךְ מֵהֶ֣ם׀ שְׁלֹשִׁ֣ים אִ֗ישׁ וַיִּקַּח֙ אֶת־חֲלִ֣יצוֹתָ֔ם - And he hit and killed them (Bare hands), thirty men and took their shirts.
וַיִּלְכֹּ֖ד שְׁלֹשׁ־מֵא֣וֹת שׁוּעָלִ֑ים - And he captured and killed (with his hands) three hundred foxes.
וַיַּ֨ךְ אוֹתָ֥ם שׁ֛וֹק עַל־יָרֵ֖ךְ מַכָּ֣ה גְדוֹלָ֑ה - And he hit them thigh on hip (Targum - horse riders and the horse with the same blow) a mighty blow. (He killed a army with his bare hands.)
We know that the blows were done by hand. As this previous Passuk, as he dismantled body parts, which cannot be done by sword. And it says the word "ויך" by all blows.
We don't question the if Samson in general is literal. So it would not make sense to question one of his superhuman feats, as it would question Samson in general, Which you are not questioning.
The Jawbone (Lechi, לְחִ֣י) weapon serves as an origin story for the Spring at Lehi called “Eye of the Crier” ( עֵ֚ין הַקּוֹרֵא֙). This geographic site “Level-Jawbone” (רָ֥מַת לֶֽחִי) is where Samson (Shimshon, שִׁמְשׁ֔וֹן) defeated the Philistines.
- While Samson was thirsty after the Philistine battle at Lehi, he prayed to find something to drink and God cleaved the socket of Samson’s weapon to make water pour out of the donkey’s jawbone. After reviving his spirit by drinking water from the donkey’s jawbone, Samson called his place of rejuvenation “Eye of the Crier” ( עֵ֚ין הַקּוֹרֵא֙). - Referencing an actual Spring of water at Lehi which Judges 15:19.
Judges / Shoftim 15:19 [MT]
“ And God cleaved the socket which was in the jawbone, and water came out of it, and he drank, and his spirit returned and he revived; therefore he called its name En-hakkore, which is in Lehi until this day. “ ( וַיִּבְקַ֨ע אֱלֹהִ֜ים אֶת־הַמַּכְתֵּ֣שׁ אֲשֶׁר־בַּלֶּ֗חִי וַיֵּצְא֨וּ מִמֶּ֚נּוּ מַ֙יִם֙ וַיֵּ֔שְׁתְּ וַתָּ֥שָׁב רוּח֖וֹ וַיֶּ֑חִי עַל־כֵּ֣ן | קָרָ֣א שְׁמָ֗הּ עֵ֚ין הַקּוֹרֵא֙ אֲשֶׁ֣ר בַּלֶּ֔חִי עַ֖ד הַיּ֥וֹם הַזֶּֽה )
The לְחִ֣י Lechi = "Jawbone" weapon was simply used as a literary device for the geographic origin story of Lehi's Spring (עֵ֚ין הַקּוֹרֵא֙)