If you’re interested in what ancient romans ate, that seems well documented.

Bread, olives (and olive oil), cheese, meat, fish, fruit, nuts, wine.

https://en.wikipedia.org/wiki/Food_in_ancient_Rome

https://en.wikipedia.org/wiki/Apicius

The majority of Italian food doesn’t actually use tomatoes. That impression is mostly because internationally-known Italian foods tend to use tomatoes (pizza for example.)

Pasta alla genovese is one such dish, it resembles modern ragu https://en.wikipedia.org/wiki/Genovese_sauce

That being said I think the ubiquitousness of tomato sauce even in modern Italian cuisine is overestimated.

Or Europeans before potatoes.

melanzana aka Aubergine aka eggplant

Honestly I find the impact of the Columbian exchange on cuisine of the old world overblown. Tomatoes potatoes and corn a sure are great, but you can do without them. Italian cuisine was different but most of the modern elements were in place. I'd say the role of tomatoes in Italian cooking isn't as big as people make it out to be.

On the other hand it's almost impossible to imagine what food was like in the Americas before Columbus. No wheat, no pork/beef/chicken, no dairy, no onions, no cabbage, no oranges/apples/figs, any citrus and much much more.