Marinara is a simple Italian tomato sauce without meat. Not difficult to make, tomatoes, onions, garlic, S and p, a little basil and/or oregano, maybe some red pepper flakes, a little stock and/or wine. It should be fairly light tasting.
Mine is not that simple partly due to me being a spice freak. This is for small things, like A pizza or a couple of sausage sandwiches.
I got dried rosemary and nothing on this planet will grind it, so I put it in a bag with some fennel and make "tea" out of it. I add some olive oil and wine at that time. While it iss brewing I cut up about half an onion and half a garlic, and lately have been putting them in the processor. The smaller the bits the better.
Then it cooks a bit as I prepare my spice battery.
1 tsp basil
1 tsp oregano
1 tsp thyme
1 tsp celery seed
½ tsp dill Weed (not Seed)
½ tsp ground ceyenne
Then goes in an eight ounce can of sauce WITHOUT SUGAR.
Then it cooks for a couple of hours. You have to add water a couple of times.
Anyone who says you don't have to cook it that long, do it and taste it every half hour and you'll understand all about spices melding and maturing.
As spicy as it seems, put it on ANYTHING and it abates the spices quite a bit.