Set-paradox

Otherwise known as ‘Russell’s paradox’. The paradox introduces us to set R: set of all sets that do not contain themselves as members.
Set is a group of different subjects which share something in common. Margaret Cuonzo in her book Paradox gives a comprehensive sample list of various sets in order of conceptual complexity which lead up to set R as the 7th entry:

“1. A set of four cups {Cup 1, Cup 2, Cup 3, Cup 4}
2. The set of natural numbers {1, 2, 3, …}
3. The set of natural numbers greater than 3, i.e., {4, 5, 6, …}
4. The set of sets that contain two members, i.e., {{a, b}, {1, 2}, {101, 102}, ...}
5. The set of all sets, i.e., {{a, b, c}, {0, 1, 2, 3, …}, {Cup 1, Cup 2, Cup 3, Cup 4}, …}
6. The set of all sets that contain themselves as members, i.e., {the set of all sets with more than 1 member, the set of all sets with more than 2 members, ...}
7. The set of all sets that don’t contain themselves as members, i.e., {the set of cups, the set of roses, the set of sets with less than two members, …}”

The paradox rises in the notion that:
Set R (the set of all sets that don’t contain themselves as members) does not include itself.
If set R doesn’t include itself as a member it should be a part of the set R.
If set R includes itself as a member then set R is not the set of all sets that don’t contain themselves as members.

I see same paradox arise within a relationship between existence and non-existence:
Existence includes everything except non-existence.
If non-existence exists, according to the fact that i am conceiving a notion of non-existence, it should be included in existence.
If non-existence is part of existence then non-existence is not non-existent.