Yes, natural language does suggest a different ontological status to different things. That observation led to the development of analytic philosophy, which analyses language to identify and correct illusions, particularly in metaphysics and ontology, that are created by ordinary grammar.
One distinction that has been made is between “count nouns” which are for things that can be counted and “mass nouns” that identify things that cannot be counted. “Table”, “Tree” and “Dog” are examples of the former and “Water”, “Sand” and “Stone” are examples of the latter. Some nouns seem to identify a physical object, but don’t. So, before they were understood, “Sky” and “Rainbow” were thought to identify physical objects, but now we know that the colours are just the effect of the sun’s light scattered by the atmosphere or by rain.
“Length” is a bit more complicated, because it is the noun corresponding to an adjective – “long” which gets its meaning by being the opposite of “short”. In the same way, the noun “Redness” corresponds to the adjective “red”, which is a property of physical objects and “anger” corresponds to “angry” which is an emotion. Grammar might lead us to believe that all these nouns must identify some physical object, but they clearly don’t. The word for this process is nominalization.
“Long” and “short” are really vague. When we want more precision, we need to invent something else. When we hold our hands apart to show how long the fish I nearly caught was, we are comparing the length of the fish to the distance between my hands. When I want to know how far it is to the next town, I can count my steps (and “step”, of course, is a count noun, but for an event, not for a physical object, but each step has a certain length). So by counting steps, we get a number for the distance, with all the conveniences that brings.
“Metre” depends on the same trick, except that it is a fraction of the distance round the earth, so it is possible to measure distances and lengths more accurately than by counting steps, which vary, not only in the same person, but also between people. So you are right. A metre is one length and two metres is a different length – twice as long as one metre. But it isn’t incorrect, because behind it, there is a process that defines a standard measure and how to use it.
You are also right that there is only one number 10 yet we often talk about 'tens' or discuss how many '5s' must be added to get 15. (I’m not going to get into the philosophy of mathematics, which is very complicated.) For present purposes, it is best to think of 10s and 5s as temporary nouns for any group of (countable) objects. In the same way, we say that there are 1,000 metres in a kilometre and so on. Then you have to add 5+5+5 to get 15, which is we say that 3 times 5 is 15.
As you can see, there are many cases of an ontologically incorrect view of their objects in natural language. I can’t think of another way of sorting out the misleading ontological implications of ordinary grammar in language than analysing and clarifying the relevant words. At one time, it was thought that formal logic was the best way to do that, but now it is recognized that it is best to rely on informal logic of the kind used in this answer.
This is often very difficult, which is what makes it fun. In your examples, “there is the class 'cat' and the type 'cat' however there is the type 'green' yet a token of green is not 'a green'”. The problem is that you are trying to use the type-token distinction where it does not apply. Colours are defined by reference to samples (each of us has our own), not by types, and the process of colour matching, which is quite different from what makes a token a token of its type. I suggest that the important difference between the class of cats and the type (as you call it) “cat” is that the class has members which satisfy a definition – again a different process from the type-token distinction.