When the LORD saw how great was man’s wickedness on earth,
and how no desire that his heart conceived
was ever anything but evil,
he regretted that he had made man on the earth,
and his heart was grieved.
. . . .
Then the LORD said to Noah:
“Go into the ark, you and all your household,
for you alone in this age have I found to be truly just.
. . . . 
Noah did just as the LORD had commanded him.
As soon as the seven days were over,
the waters of the flood came upon the earth.
(Gen 6:5-8;7:1-5,10)

Even though God’s “heart was grieved,” Noah and his family and all the animals are saved. And so the ark becomes a symbol of salvation.