But here's the thing. Neutral is both the default of all living things in the setting (all animals are Neutral), and pretty much every definition of the other alignments involves going above and beyond normal in that direction.
Sitting at home, minding your own business, and petting a dog every once in a while is not enough to be Good. You have to sacrifice, you have to go out of your way to help others, you have to do more than the absolute baseline amount expected to not be driven out of town.
Same with being Evil. Grumpy and saying mean things isn't enough to be Evil. It takes actively hurting people (or being completely okay with actively hurting someone) in some way to get to that point.
No strong feelings for or against that would cause you to take up arms or join an activist group? Neutral. Keeping your head down and taking care of your family and letting everybody else take care of theirs? Neutral.
Chaotic doesn't just jaywalk, they try to overthrow institutions. Good doesn't just donate a copper to a beggar every once in a while, they open and run homeless shelters.
If the definition of the alignment involves "this is how its different from normal", then "normal" must be Neutral.