Regarding your first question.
To define an idea as being "Jewish", we must be bound by some sort of text. Some of the "non-jewish" concepts that they have stood by, are based on Jewish sources. This entire idea of one person, taking the sacrifice for many sins is based on Yeshayahu 53. It is pretty clear and apparent in the reading of the texts that there is a concept of this.
We must remember that the Christian culture is deeply intertwined with the Jewish one. From its roots and through its history. We might think that their ideas are "non-jewish" at their core when in fact they are Jewish just the same.
The idea of one man bearing the sins of all through pain and suffering is the literal translation of Chapter 54. Probably based off those texts, the entire christian culture built their own. The only critique we can make, is the idea of taking one Chapter and basing an entire religion on it and ignoring the rest of the texts.
Here are a couple of verses to illustrate the point:
(ו) כֻּלָּ֙נוּ֙ כַּצֹּ֣אן תָּעִ֔ינוּ אִ֥ישׁ לְדַרְכּ֖וֹ פָּנִ֑ינוּ וַיהֹוָה֙ הִפְגִּ֣יעַ בּ֔וֹ אֵ֖ת עֲוֺ֥ן כֻּלָּֽנוּ׃
All we like sheep did go astray, We turned every one to his own way; And the Lord hath made to light on him The iniquity of us all.
(ה) וְהוּא֙ מְחֹלָ֣ל מִפְּשָׁעֵ֔נוּ מְדֻכָּ֖א מֵעֲוֺנֹתֵ֑ינוּ מוּסַ֤ר שְׁלוֹמֵ֙נוּ֙ עָלָ֔יו וּבַחֲבֻרָת֖וֹ נִרְפָּא־לָֽנוּ׃
But he was wounded because of our transgressions, He was crushed because of our iniquities: The chastisement of our welfare was upon him, And with his stripes we were healed.
אָכֵ֤ן חֳלָיֵ֙נוּ֙ ה֣וּא נָשָׂ֔א וּמַכְאֹבֵ֖ינוּ סְבָלָ֑ם וַאֲנַ֣חְנוּ חֲשַׁבְנֻ֔הוּ נָג֛וּעַ מֻכֵּ֥ה אֱלֹהִ֖ים וּמְעֻנֶּֽה׃
Surely our diseases he did bear, and our pains he carried; Whereas we did esteem him stricken, Smitten of God, and afflicted.
The texts that are not accounted for are, such as the ones in Yechezkel 18, about each man being responsible for their own sins.
We can see how living by the concept of an individual taking the role of society, can lead to godifing the individual.
As stated in the comments, of later Chasidic thought basing the verse in Mishle of "Tzadik Yisod Olam" to be quite literal. This is deeply aligned with Isiah 53 and a very Jewish concept. There is an obvious danger with it as made known in many societies.
David counts the Jewish nation wrongly and thousands of people die. Avraham hopes to find some righteous people to save an entire city. We see the idea of the power of influence in the individual, based on a development of relationship with God.
I think according to the "jewish concept" we must juggle the idea of personal responsibility with the idea of an individual being "responsible" for the whole. What makes it "non-jewish" is only believing in one of these concepts without the other, in my opinion.
Regarding your second question, if commentators mean on this concept itself. I saw that Rashi and Ibn Caspi on Yeshayah 53, define the texts as a parable to the entirety of the Jewish nation in relation to the world. It still is a concept but, more global in their approach. Others see it more literal (ramban, ibn ezrah, radak)
If "commentators" mean on the Gemarah you quoted I don't have the answer.
I don't think Yeshayahu is the earliest source to this but, the most detailed. I mentioned David sinning and causing havoc on the nation. (which means he has the influence of the entire nation for good or bad). And Avraham pleading for the Tzadik to save an entire city.