לא ידון רוחי באדם לעולם בשגם הוא בשר, it is intolerable that there will continue the argument, strife before Me allowing (the angels?) to claim that although seeing that man has been endowed with divine qualities he must be punished, whereas his close ties to physical earth must be considered as excuses for his conduct, entitling him to continued mercy, and indulgence by Me.

והיו ימיו, he will be given a certain length of time within which to repent his sins;

מאה ועשרים שנה, during which time Noach would have time to construct the ark, and by doing so rebuking and warning people of what is in store for them. (compare Sanhedrin 108)

הנפילים היו בארץ בימים ההם, these giants were not about until the last 120 years which G’d had assigned man as a grace period within which to do teshuvah וגם אחר כן, as well as thereafter, i.e. they did not repent and mend their ways at all.

כי רבה רעת האדם, a reference to the past,

וכל יצר לב האדם, a reference to the future (when it would not improve)

ויתעצב אל לבו, seeing that G’d does not want even the guilty to die instead of finding their way back. The opposite “emotion” of G’d to the one expressed here is found in Psalms 104,31 ישמח ה' במעשיו, “the Lord ‘enjoys’ the deeds of His creatures.”

But Noach found favor (chen). Chen implies groundless favor. Because Noach did not actively spread knowledge of Hashem he was not worthy that others should be saved on his account. Thus it was an act of groundless favor to him that his sons and daughters-in-law were spared.

תולדות נח, a reference to his history, commencing with his own life and continuing with that of his offspring.

צדיק, in his deeds,

תמים, in his attitudes,

בדורותיו, according to the generations during which he lived. They included part of the generation of Metushelach, of Lemech, and those during the 600 years preceding the deluge.

את האלוקים התהלך נח, he walked in G’d’s way trying to be helpful to others, and to instruct and if necessary to rebuke them, as our sages pointed out. This is also in accordance with what the historian Berussi Hacaldaii (3rd century B.C.) wrote about him.

ויולד נח, as soon as he began to rebuke his fellowmen he was granted children

והנה נשחתה, without external influences, as a natural consequence, not due to man’s ecologically criminal behaviour. Although on the surface, there appeared to be no connection, man’s corruption resulted in the corruption of his habitat. The language used here by the Torah is comparable to Isaiah 47,2 וטחני קמח, “and grind meal.” One does not grind flour, but one grinds grain into flour. The prophet spoke about the end product. The Torah also spoke about the end product of man’s corruption bringing in its wake, though invisibly, the destruction of the earth’s crust.

The end of all flesh. That is, the end of their 120 year reprieve.

בא לפני, this period has now expired.

The earth is filled with violent crime. A landlord would steal openly from his tenant farmer while the tenant farmer stole surreptitiously from the landlord in return. Thus all the earth’s bounty went to thieves.

והנני משחיתם את הארץ, so that now I will destroy them together with the earth. I will destroy the climate which could support life on earth by interfering with the sun’s orbit and rearranging it from the beginning of the deluge for the entire future. We find that G’d explained this to Job In Job 38, 4-15. This accounts for the lifespan of man having been drastically reduced after the deluge. The climate of the earth changed, there were greater extremes of heat and cold, the produce of the earth was considerably less capable of supporting a long lifespan. As a by-product of this deterioration in the quality of the vegetable products, man was allowed to eat meat as a compensation.

עשה לך תבת וגו, during the period allocated to them, in order to remind them to do teshuvah.

בצדה תשים, on the side which is wide, for that is the side called צד. The long side is referred to as צלע.

תחתיים, the lower deck in ships; as in any other ship, the customary lower deck.

שניים ושלשים, they are similar, parallel to the lower deck.

ואני הנני מביא את המבול, G’d is saying, that Noach’s task is to build the ark, whereas He, when the time expires, will bring on the deluge He had threatened as soon as the ark would be completed. The word מבול is a variant of מפלה, referring to something lost as in Deut. 14,21 כל נבלה, a carcass being a life lost. The definitive article ה in המבול refers to the destruction, the nature of which had not previously been spelled out. [my paraphrasing. Ed.]

והקימותי את בריתי, a reference to the covenant G’d made with Noach after the deluge.

ואתה קח לך מכל מאכל, different menus for different species of creatures.