Do you really think “that Cardinality is first of all a measurement unit of the existence of things”?
Let’s try that, for set X of all possible values of the variable Y we have {Y1, Y2, Y3… YZ}. The cardinality of set X then = Z.
If Y can take no value, say as the value of any irrational number in the set of positive integers, then set X is the empty set and Z=0. If Y can only take one value in one instance as 0, say as the number of irrational numbers in the set of positive integers then set X is {0} and Z=1. If Y can also only take the value 0 in multiple instances as the number of irrational numbers in the set of positive integers between any two positive integers “I” such as YN as the number of irrational number in the set of positive integers in the interval [IN, IN+1) Thus Y1 = 0, Y2 = 0, Y3 = 0 …..YN = 0, then Z = N = ¥.
In all cases the variably Y exists as part of the definition of set X. Set X exists whether or not variable Y can take only one value in one instance, always takes the same value or different values in multiple instances, or can take no value, as does the cardinality of set X as Z. Also in all cases the variable Y goes to the lack of existence of irrational numbers in the set of positive integers. So exactly what “things” is the value Z “a measurement unit of the existence of” other then simply the cardinality or size of set X depending on how the variable Y is used to demonstrate the lack of existence of irrational numbers in the set of positive integers?
In your example Y is an existing thing that measures the non-existence of things.
Y cannot be a member to some set (say X) if it does not exist, and the Cardinality of X (called Z) is the measurement unit of the existence of Y as a member of X.
If X has no members, then the existing X is an atom, where atom is an existing thing that has no sub-existing things.
For example:
{} is an atom (it is an existing thing that has no sub-existing things).
On the contrary {{}} is not an atom (it is a complex) and it is the result of the linkage between two different aspects of the atomic state (that are not derived from each other), which are:
The non-local atom (represented by the outer "{" "}" of complex "{{}}").
The local atom (represented by the internal "{}" as the member of the complex "{{}}", where "{}" it is not a sub-thing of the non-local atom).
From this novel view, the existing levels of sets are not ignored, and as a result Cardinality is the measurement unit of any possible existence of some set including the existence of levels under some Non-locality\Locality Linkage.
Set is an existing thing that can be an atom (in the case of {}, and in this case we do not distinguish between Non-local atom and Local atom), or it can be a complex (in the case of at least {{}}, and in this case we do distinguish between two atomic aspects (Non-local atom and Local atom) as the fundamental buildings blocks of the complex).
By not ignoring Complexity (as Standard Math does) Cardinality must be the measurement unit of any possible existence of some set including the existence of levels under some Complexity.
The non-finite levels between Non-locality and Locality are represented as:
{…{{{…{}…}}}…}, where the outer "{" "}" represents the non-local aspect of the complex, and the inner "{}" represents the local aspect of the complex.
The cardinality of {…{{{…{}…}}}…} = |{…{{{…{}…}}}…}| = 0+1+1+1+…<
∞