That's like saying Huckleberry Finn doesn't exist. Just because it's made-up doesn't mean it doesn't exist. It exists as a concept which billions of people understand.
Turns out you can make up any arbitrary distinctions and they just start existing. The question is if they severe any useful purpose.
I can make zodiac 2.0 exist by adding shoe size to distinguish between regular aquarius and aquarius without platypus (above EU 42 is with). So now the Zodiac 2.0 exists with the same predictive power as 1.0.
Considering how the universe is full of stuff circling around stuff circling around stuff circling around... the zodiac signs have moved over the last couple of millenias.
Actually they do. The zodiac sign constellation of a day correspond to the constellation over which the sun while be at noon. So you do have a zodiac sign constellation associated to your day of bird.
But depending on how your culture group stars in constellations you might be from a different zodiac.
If you want to follow a classical westerner map of the sky, they will be 13 of them.
Also, note that the zodiac signs won't cut the year in equal parts. Some constellations are just bigger than other and the sun path across the sky changes more or less quickly from a day to another depending on the time of the year.
The actual signs exist (get yourself a planisphere or a stargazing app, find some dark skies, and discover them for yourself!), it's just all the magic personality nonsense associated with them is bullshit.
Pfffft if none of them exist then how did the Rat play a flute while standing on the head of the Ox to impress the Jade Emperor and become the first zodiac sign?
Zodiac signs are literally constellations... Which are quite real.
Astrology is also real, in the fact that it's a uselessly real thing. Women love it though. Same with tarot. All you do is make plausible sounding shit up and then they placebo themselves into happiness or nocebo into a sour mood.
The people that get the angriest about astrology understand it the least. They think that you're supposed to tell who you are by looking at one thing, and that couldn't be farther from the truth.
In reality, it's a very complex equation with multiple variables that change over time. People don't understand that your chart reflects many different signs, and where the signs exist on your chart at certain times can describe aspects of your personality.
Having Aries as your sun sign means something different than having Aries as your moon sign. But they still contribute to a larger picture. And then on top of that, depending on if you live out of more negative or positive aspects of your personality can bring out different traits that might not have much to do with your sign at all.