« Ce » is only used for objects and sometimes for non-human living creatures (depends of the relation you have with it). It’s a little bit like « it » in English. In fact, most of the times, if you would refer to something as « it », use « ce » instead of « celui », « celle », « ceux », …

In your case, « ce qui » means « the thing that », but « ceux qui » means « those who ». It has a perfectly similar meaning, except that the subject is once « it » and once « they ».

• Ce qui can refer to a previous part of the sentance or the text: in a certain way, you can compare ce to the english word which in that context:

J’ai trouvé un travail, ce qui est bien.
I have found a job, which is a good thing.

• Ce qui can also refer to something (but not somebody) for a future reference:

Ce qui se trouve sur cette table me semble bon.

For somebody, we would use celui qui (masc) / celle qui (fem) / ceux qui (plur) instead:

Ceux qui sont venus m’aider sont très gentils.
Those who came to help me are very kind.

• We say ce monsieur, ce plombier, cet agent, ce bureau, cette table, etc, to refer to someone or something. We can then refer to it using qui by saying celui/celle/ceux qui, not ce qui:

-Ce gars est sympathique.
-De qui parles-tu ?
-Je parle de celui qui est assis sur la chaise, à côté de la table.

-This guy is really nice.
-Who are you referring to?
-I’m referring to the the guy sitting on the chair, close to the table.