I think it's time to take a position of no stupid questions. Why?
Well, aside from the fact that you can order a pre-bottled Campari & Soda in many countries, perhaps you've seen lamps made out of Campari Soda bottles? Chances are that isn't what you have on hand. In a rare change of form, I'll answer the question before telling a rambling story. A Campari Soda is just 1 part Campari and 2 parts soda. But, the way to take the recipe seriously is:
Campari Soda
Fill a highball glass AKA tall/ collins/ glass completely with ice, then pour
1 1/2 ounces Campari
3 ounces pre-chilled soda water
stir to mix into a uniform color and top with an orange or lemon zest
no straw, almost every cocktail is better without a straw
So yeah, it's not dumb to ask, a cocktail isn't just ratios, it's glassware, presentation, the way you treat ingredients and the thousand tiny decisions you make on the way. It's really the only difference between a pro and a rookie— understanding many decisions are made to create a simple result.
simple templates and tips of aperitivos (aperitivi) highballs, spritzes, Negroni-style and bitters/ aperitvo/ amaro spiced exotic cocktails
So for real, honest truth: fuck a Negroni without Campari. That said, Cappelletti makes a better spritz, Melleti 1870 has great spicy notes that I think would be better for fruit juice cocktails. Gran Classico is thick, hold up well to cocktails served on ice. St George Bruto has an herbal, fir note that I think it great in stirred drinks. Punch reviewed many of the red bitters on the American market, check that piece out here.