Additive primary colors are necessary when you have no light, and need to create color. Think a black screen, and you are creating colors with RGB pixels.

Subtractive primary colors are necessary when you have full-spectrum (white) light and need to filter down to a single color.

Other "primary" colors, such as the red, blue, yellow pigment primaries we learned in Kindergarten exist because pigments historical couldn't be created perfectly, and those "primaries" are the best way of getting the most colors, but still have a very limited (by comparison) gamut.

Why are there 3 primary colors (regardless of which 3 you pick)? That has nothing to do with the nature of light, and everything to do with the fact that humans see light using 3 distinct frequency response curves [0]. This means that humans perceive color as a 3 dimensional space; and the role of the primary colors is to pick a point in this space by selectively stimulating or masking the 3 response curves. In a world of pure linear algebra, almost any 3 colors would do, but physical reality limits how ideally we can mix them; and how much light they can emit/mask.

Further, the 3 response curves are overlapping, so there is no set of ideal colors that would let you actually control the 3 curves independently.

[0] At least for color perception in a typical human.

"Cyan" is a very bad word choice caused by confusions in the translations of Ancient Greek texts made by philologists ignorant of chemistry and mineralogy. In Ancient Greek, "cyan" meant pure blue, not blue-green. More precisely, it was the color of the ultramarine blue pigment, the most expensive blue pigment at that time, which was imported from the present territory of Afghanistan and for which the name "ku-wa-no" was already used by the Hittites, a millennium before the Greeks. Nowadays ultramarine blue is still used as a pigment, but it is made synthetically, so its cost is a small fraction of what it was before the 19th century.

Before the use of "cyan" has started, the color name "blue-green" had been used for a very long time. Similarly, "orange" is a relatively new English word, but the color had been mentioned for many centuries, as "red-yellow" or "yellow-red".

So the awareness of distinct hues is not necessarily limited to the set of simple color words, because most languages have used compound words to name the hues for which they did not have a simple word.

Other languages have used the names of well-known colored objects to distinguish the hues that did not have distinct names. For instance, in Latin the word for "red" was used for both red colors and purple colors. When Latin speakers wanted to specify whether something was red or purple, they would say "red like the kermes (red) dye" or "red like the purple dye" (the word "purple" as a color name comes from the latter expression). Similarly, in Latin the word for green meant either green or blue-green. To distinguish the 2 colors, a Latin speaker would say "green like grass" or "green like leaves" or "green like emeralds" for expressing "green" and "green like the littoral sea" or "green like beryls" or "green like turquoise gems" for expressing "blue-green". So they were well aware about the differences between these colors, even if they did not have distinct words for them.

Is it even a wheel though?

The most common green color from excited nitrogen molecules going back to normal by emitting 557.7 nanometer photons. Oxygen makes 650 nm red, and the 427.8 nm blue is from nitrogen ions.