Um.
I mean, I like your attitude to the debate, but I don't really get it.
"A is not B." "No, A is a B, but B is not the same as A."
"Ah, but, there is no such thing as an alphabet, really, it's all just vibrations in the air or marks on paper."
You can dismiss almost any argument in science by deconstructing it to symbols and then saying that symbols are not real, but I don't see this as a valid contribution to the debate, myself. Your mileage clearly varies.
There absolutely is such a thing as "a tree". Trees are a real thing. They are an identifiable type of land plant.
But "tree" is a growth habit. It's not a family of plants. This is an important distinction and it's not a hard one to grasp. I still find it odd that it surprises people.
Similarly, I have zero time for this "no such thing as a fish" bollocks. Yes there is such a thing as a fish. It's an obligately aquatic, legless, gilled vertebrate.
It is quite easy to define what "fish" means in unambiguous terms that exclude tadpoles, axolotls, terrestrial vertebrates such as humans and so on.
The argument seems to rest on their being (at least) two families of fish. Big deal. Fish are real, trees are real. They aren't families, but they are identifiable groups.