Originally, marinara sauce actually did not have any seafood in it. The name is derived from the Italian word for sailor but it was the name for a sauce that was made when the sailors returned from the sea. The sauce is originally from Naples and was also used as a topping for pizza which also came from Naples.
Tomato paste and tomato sauce are two different things. The basic Italian tomato sauce is a pomodoro and everyone has their own recipe but it's pretty basic: Tomatoes, Garlic, Olive Oil, Onion, Celery, and/or Carrot, White Wine (optional).