But Americans didn't name it marinara...? It's an Italian word. I mean, and Italy is surrounded by water. So seafaring people, they be.

Wiki:

Origin

Cooks aboard Napolitan ships invented marinara sauce in the mid-16th century after Spaniards introduced the tomato (a New World vegetable) to Europe. This meat-free sauce was easy to make and resisted spoiling due to the high acid content of tomatoes.[9] This made it ideal for lengthy sea voyages hundreds of years before refrigeration methods were invented.

Marinara spaghetti = Mariner's spaghetti. It's sauce that mariners invented to withstand the voyage without spoiling.