The E.U. is clearly an example of the economic interdependency theory. It evolved in post-WW2 Europe from the European Coal and Steel Community. Mineral richness is why the Saarland was given to France after WW2. The idea is that economic integration will lead to political integration from the ground up.

My understanding of the pre-WW1 alliances is that they were deals made between a lot of people with “Habsburg” in their names.

Dynastic politics were by and large dead in the 1800s with few exceptions (but generally kings/queens were just pawns in the hand of the politicians unlike in the preceding centuries).

The last dictatorship was in the 1970s? The last World War the 40s? The US might have had a civil war but it went in and came out the other side with the same borders, government, and constitution. Still going strong since the 18th century.

This is a bad take on the cause of alliances. large wartime coalitions had been a thing since the consolidation of power into monarchies in Europe: the 7-year war had involved all of Europe's significant actors, as did the napoleonic wars, the war for the spanish succession, the 30-year war, etc. This was much earlier than the development of cross-border trade.

In an imperialist era, diplomacy was the way to coordinate European nations' colonial efforts without repeating that kind of conflict. It was only temporary, though, since expansionist policies can't last forever peacefully.

The reason WW1 felt so different from previous wars was technological development. That aspect was already present in earlier wars, WW1 was just the first major European conflict in a long time.