existing vs being

existing is not a noun while being is a noun.

Word	Noun	Adjective	Verb	Adverb
existing	No	Yes	No	No
being	Yes	No	No	No

existing (noun)	being (noun)
	a living thing that has (or can develop) the ability to act or function independently
	the state or fact of existing

existing (adjective)	being (adjective)
having existence or being or actuality
presently existing
existing in something specified