Nahum Sarna, Understanding Genesis, page 3
What is the Torah's message about the nature of humankind from this account of humanity's creation in Genesis 1?
(ה) כֵּיצַד מְאַיְּמִין אֶת הָעֵדִים עַל עֵדֵי נְפָשׁוֹת... לְפִיכָךְ נִבְרָא אָדָם יְחִידִי, לְלַמֶּדְךָ, שֶׁכָּל הַמְאַבֵּד נֶפֶשׁ אַחַת מִיִּשְׂרָאֵל, מַעֲלֶה עָלָיו הַכָּתוּב כְּאִלּוּ אִבֵּד עוֹלָם מָלֵא. וְכָל הַמְקַיֵּם נֶפֶשׁ אַחַת (מִיִּשְׂרָאֵל), מַעֲלֶה עָלָיו הַכָּתוּב כְּאִלּוּ קִיֵּם עוֹלָם מָלֵא.
וּמִפְּנֵי שְׁלוֹם הַבְּרִיּוֹת, שֶׁלֹּא יֹאמַר אָדָם לַחֲבֵרוֹ אַבָּא גָדוֹל מֵאָבִיךָ.
וְשֶׁלֹּא יְהוּ מִינִין אוֹמְרִים, הַרְבֵּה רָשֻׁיּוֹת בַּשָּׁמָיִם.
וּלְהַגִּיד גְּדֻלָּתוֹ שֶׁל הַקָּדוֹשׁ בָּרוּךְ הוּא, שֶׁאָדָם טוֹבֵעַ כַּמָּה מַטְבְּעוֹת בְּחוֹתָם אֶחָד וְכֻלָּן דּוֹמִין זֶה לָזֶה, וּמֶלֶךְ מַלְכֵי הַמְּלָכִים הַקָּדוֹשׁ בָּרוּךְ הוּא טָבַע כָּל אָדָם בְּחוֹתָמוֹ שֶׁל אָדָם הָרִאשׁוֹן וְאֵין אֶחָד מֵהֶן דּוֹמֶה לַחֲבֵרוֹ. לְפִיכָךְ כָּל אֶחָד וְאֶחָד חַיָּב לוֹמַר, בִּשְׁבִילִי נִבְרָא הָעוֹלָם...
(5) How do we interogate witnesses in a capital case? "It was for this reason that humanity were first created as one person , to teach you 1) that anyone who destroys a life is considered by Scripture to have destroyed an entire world; and anyone who saves a life is as if he saved an entire world."
2)And also, to promote peace among the creations, that no person would say to her/his friend, "My ancestors are greater than yours."
3) And also, so that heretics will not say, "there are many rulers up in Heaven."
And also, to express the grandeur of The Blessed Holy One: For a human strikes many coins from the same die, and all the coins are alike. But the King, the King of Kings, The Holy Blessed One strikes each human from the die of the First Human, and yet no person is quite like her/his friend. Therefore, every person must say, “For my sake the world was created.” ...
MS Cambridge c. 1400

