Those who died weren't still there after the war. Those of them who didn't have any children left behind were effectively genetically exterminated - ending millions of years of their genetic heritage. And cultural heritage.
It was the greatest disasters in the history of Europe, and the effects are still deeply felt. The world wars were the greatest idiocy in the history of humanity.
The European land mass is of course there. The European people(s) have been significantly altered from what they were and what they would have been if it wasn't for those wars.
