The important event in Gn 9 is the covenant or promise God made to Noah after the flood was over. The first thing that happens is that Noah is given certain responsibilities from God like they can’t eat an animal alive, not to kill another human being, and to repopulate the world. Next God promises Noah that he would not create another flood like the one he just witnessed, a worldwide flood. Finally to show God would keep his promise, every time there will be a long period of rain a symbol would appear to show the end. The promised symbol was a rainbow.
"Be fertile and multiply and fill the earth... Only meat with its lifeblood till in it you shall not eat" (Gn 9:1,4)
"I will establish my covenant with you, that never again shall all creatures be destroyed by the waters of a flood; there shall not be another flood to devastate the earth" (Gn 9:10).
"I set my bow in the clouds to serve sign of the covenant between me and the earth" (Gn 9:13)
God is faithful and loving. God always keeps his promises.