Some people believe WW2 started many years earlier, but most historians don't put the start date at the conflicts going on before the war became intercontinental with sides working together on a global scale.
War has still been going on since 1945, much earlier if not always, so akshually WW2 never ended or is just how it's always been? (mostly in places that are not "first world" / The West)
There's a simple and very logical definition of what a "world war" is - it's when international law completely breaks down, and the only way to get back to a semblance of order in international relations is to have the victors of the ensuing shitstorm impose a new set of rules in some sort of grand finale pact.
1945 was clearly that. 1920 with the League of Nations attempted to be that, but failed.
Whatever happens after the current turbulence we can be sure that there won't be a UN and NATO and a World Bank at the end.
P.S. The first modern world war was the Thirty Year's War.
Because the UN, NATO, etc., are clearly not working now. They're not gonna be fixed to work as designed because that's quite impossible in today's world.
Akshually there is, and WW3 has been going on since 2010. (Mostly in places that aren't Europe.)