Keruvim (Art) vs. Nechushtan (Idol)
In [Exodus 20:4-5] a פֶ֣סֶל Pesel is an Idol, not just illustrative Art. - Any פֶ֣סֶל Pesel is a 'sculpture' worshipped as a representative of some diety like Dagon or the Nechushtan.
Keruvim כְּרֻבִ֖ים in [Exodus 25:19-20] were sculptures , but these artistic 3D representations of heavenly Mal'akim מַלְאָכִים "angels" were not worshipped.
[Shemot | Exodus 25:19]
Make one Keruv at one end and the other cherub at the other end; of one piece with the cover shall you make The-Keruvim at its two ends. (וַ֠עֲשֵׂ֠ה כְּר֨וּב אֶחָ֤ד מִקָּצָה֙ מִזֶּ֔ה וּכְרוּב־אֶחָ֥ד מִקָּצָ֖ה מִזֶּ֑ה מִן־הַכַּפֹּ֛רֶת תַּעֲשׂ֥וּ אֶת־הַכְּרֻבִ֖ים עַל־שְׁנֵ֥י קְצוֹתָֽיו)
The Art Design of Keruvim : [ Exodus 25:20 ]
"The-Keruvim shall have their wings spread out above, shielding the cover with their wings. They shall confront each other, the faces of the Keruvim being turned toward the cover." (וְהָי֣וּ הַכְּרֻבִים֩ פֹּרְשֵׂ֨י כְנָפַ֜יִם לְמַ֗עְלָה סֹכְכִ֤ים בְּכַנְפֵיהֶם֙ עַל־הַכַּפֹּ֔רֶת וּפְנֵיהֶ֖ם אִ֣ישׁ אֶל־אָחִ֑יו אֶ֨ל־הַכַּפֹּ֔רֶת יִהְי֖וּ פְּנֵ֥י הַכְּרֻבִֽים)
YHVH - Elohim eternally living without form - tells Moshe that He will be present between the Keruvim statues in [Exodus 25:22] : "There I will meet with you, and I will impart to you—from above the cover, from between the two Keruvim that are on top of the Ark of the Pact—all that I will command you concerning the Israelite people." (וְנוֹעַדְתִּ֣י לְךָ֮ שָׁם֒ וְדִבַּרְתִּ֨י אִתְּךָ֜ מֵעַ֣ל הַכַּפֹּ֗רֶת מִבֵּין֙ שְׁנֵ֣י הַכְּרֻבִ֔ים אֲשֶׁ֖ר עַל־אֲר֣וֹן הָעֵדֻ֑ת אֵ֣ת כׇּל־אֲשֶׁ֧ר אֲצַוֶּ֛ה אוֹתְךָ֖ אֶל־בְּנֵ֥י יִשְׂרָאֵֽל)
Were these artistic 3D Keruvim "statues" on the Ark covering - actually פְּסָלִים Pesalim : idols? - No. | Moshe & Aharon worshipped YHVH between the Keruvim.
In [Divrei Hayamim II - 2 Chronicles 7:7], King שְׁלֹמֹ֗ה Shlomoh designs כְּרוּבִ֖ים Keruvim on the walls of the "House of YHVH": "And he overlaid the House; the beams, the sideposts and its walls and its doors with gold, and he engraved Keruvim on the walls." (וַיְחַ֨ף אֶת־הַבַּ֜יִת הַקֹּר֧וֹת הַסִּפִּ֛ים וְקִֽירוֹתָ֥יו וְדַלְתוֹתָ֖יו זָהָ֑ב וּפִתַּ֥ח כְּרוּבִ֖ים עַל־הַקִּירֽוֹת)
Then King Shlomoh creates two new large-scale gold representations of Keruvim in addition to the Keruvim above the ark covering. [Divrei Hayamim II - 2 Chronicles 7:10-13] . The design of these 4-Keruvim statues are represented differently in the vision of in יְחֶזְקֵ֨אל Yechezeqel [Ezekiel 10], but none of the Keruvim are worshipped by King Shlomoh or Yechezeqel.
Since artistic 3D statues of Keruvim are inspired by YHVH & not worshipped by men, then we can understand [Exodus 20:4-5] means that a forbidden Pesel is a "sculpture" which men worship (bow/pray to) like the pesel Dagon in [1 Samuel 5:2] : "And the Philistines took the Ark of God and brought it to the house of Dagon, and set it up beside Dagon." (וַיִּקְח֚וּ פְלִשְׁתִּים֙ אֶת־אֲר֣וֹן הָאֱלֹהִ֔ים וַיָּבִ֥אוּ אֹת֖וֹ בֵּ֣ית דָּג֑וֹן וַיַּצִּ֥יגוּ אֹת֖וֹ אֵ֥צֶל דָּגֽוֹן) --- The artistically decorated, keruvim-covered Aron אֲר֨וֹן "Ark" representing the Word of YHVH destroys the pesel (worshipped-statue) of Dagon in [1 Samuel 5:4].
If you draw a picture, or sculpt a statue - Do Not bow to it / talk to it / pray to it / ask it for help. | These prohibited actions transform Art into an Idol.
The נְחֻשְׁתָּֽן Nechushtan : When Art turns into an Idol
[Melakim II - 2 Kings 18:4]
"He (Hezekiah) abolished the high places, and smashed the monuments, and cut down the asherah, and crushed the copper serpent that Moshe had made, for until those days the children of Israel were burning incense to it; and he called it Nechushtan." (ה֣וּא | הֵסִ֣יר אֶת־הַבָּמ֗וֹת וְשִׁבַּר֙ אֶת־הַמַּצֵּבֹ֔ת וְכָרַ֖ת אֶת־הָֽאֲשֵׁרָ֑ה וכִּתַּת֩ נְחַ֨שׁ הַנְּח֜שֶׁת אֲשֶׁר־עָשָֹ֣ה מֹשֶׁ֗ה כִּ֣י עַד־הַיָּמִ֚ים הָהֵ֙מָּה֙ הָי֚וּ בְנֵֽי־יִשְׂרָאֵל֙ מְקַטְּרִ֣ים ל֔וֹ וַיִּקְרָא־ל֖וֹ נְחֻשְׁתָּֽן)