The whole shape of the kayak evolved for hunting in a specialized environment. For the modern recreational paddler near Greenland replicas are demanding/dangerous compared to wider modern kayaks.

I agree overhangs are mostly to deal with ice. Some overhangs are low and long others high and short with most somewhere in between. Some do spear into waves others have quite voluminous bows that climb waves well. The deeper you look the more variation you see in their design. Some even had ends similar to Mackenzie Inuit kayaks as in H.C. Petersen's book

Not all parts of the Greenland coast have winter pack ice , the south-west coast is largely ice free year round , this feature also provides a winter habitat for millions of sea birds and sea birds were hunted.

Think of Greenland as one big glacier and with daily temperature variations the high altitude ice pack frequently sends hurricane force winds descending the steep walled inlets and out into bays with little warning. A shallow kayak is a definite advantage.

Someone mentioned ribs were chewed to soften , that may be but for sure ribs were crimped with the teeth to bend at just the right spot

Harvey Golden's great book shows the variation of Greenland kayaks to be quite large and steadily evolving.