The Flood narrative is complex. Human society had populated the world, and initially fulfilled its mission, until they lost their way, and degenerated to a point where things needed to start over.
What went wrong?
The Torah emphasizes Noach’s role as a partner with all living things:
צֵא, מִן-הַתֵּבָה–אַתָּה… כָּל-הַחַיָּה אֲשֶׁר-אִתְּךָ מִכָּל-בָּשָׂר, בָּעוֹף וּבַבְּהֵמָה וּבְכָל-הָרֶמֶשׂ הָרֹמֵשׂ עַל-הָאָרֶץ–הוצא (הַיְצֵא) אִתָּךְ; וְשָׁרְצוּ בָאָרֶץ, וּפָרוּ וְרָבוּ עַל-הָאָרֶץ – Leave the Ark; you… and every creature with you. Every creature, bird, animal and insect that creeps on the earth, should leave with you. They will multiply and infest the earth. (8:16-17)
The Malbim explains that the partnership aspect was beyond the fact their survival was due to the fact they were physically with him.
Humans are created with the gift of free will. When Adam and Eve, as the only people in the world, corrupted their moral freedom, the consequences were dire, and the same almost happened once again; an entire generation collectively squandered their moral consciousness, defeating the purpose of their creation. The moral fabric of the world disintegrated to a point where the Torah states that all hope was lost:
כִּי-הִשְׁחִית כָּל-בָּשָׂר אֶת-דַּרְכּוֹ, עַל-הָאָרֶץ – that every living creature had lost its way… (6:12)
Noach reclaimed and preserved decency, and “humanity” – in the true sense of the word, by exerting his moral freedom for honesty and goodness. As the sole creature not to lose his way, existence could linger on exclusively for his sake. The entire planet owed him a life debt, and this is the partnership the Torah refers to:
צֵא, מִן-הַתֵּבָה–אַתָּה… כָּל-הַחַיָּה אֲשֶׁר-אִתְּךָ מִכָּל-בָּשָׂר, בָּעוֹף וּבַבְּהֵמָה וּבְכָל-הָרֶמֶשׂ הָרֹמֵשׂ עַל-הָאָרֶץ–הוצא (הַיְצֵא) אִתָּךְ; וְשָׁרְצוּ בָאָרֶץ, וּפָרוּ וְרָבוּ עַל-הָאָרֶץ – Leave the Ark – you… Every living creature with you. Every creature, bird, animal and insect that creeps on the earth, should leave with you, and they will multiply and infest the earth. (8:16-17)
Nature literally survived through him – אִתְּךָ. It therefore follows that after this event, humanity is permitted to consume meat for the very first time.
By rising above a failing world, Noach set humanity aside as being the noblest of all creatures.