Celestial bodies array broadly in size and shape, and one of these (Ophiuchus) just isn't even included in the zodiac even though the Sunlight routinely passes via it. The traditional Greeks referred to the region within the ecliptic like a zodiac, “the small animals,” or zodiacs kyklos, “circle of animals,” https://www.trulydivine.com/sun-moon/aquarius-sun-with-libra-moon-and-aries-rising