Even if climate change was true for every geographical region that gets affected by rising ocean levels there will be even greater areas of the world that previously weren’t inhabitable that wil become productive regions for people to live, as you say the climate of this planet has been evolving and changing since the day it was created
There are ROMAN docks and ruins under water all around the coasts of southern and western Europe.
Those chariots caused the seas to rise, no doubt.............