Various grammar references note the illogic of aren't I
as a tag question, but all describe its existence.
As a very formal alternative, you could use am I not,
I'm a human being, am I not?
As well as the conversational:
I'm a human being, aren't I?
Some grammar references show that ain't I has historically
been only marginally acceptable. Celce-Murcia and Larsen-Freeman (The
Grammar Book, Heinle & Heinle, 1999, p. 218) suggest that aren't
I arose from the "strong social and educational stigmas against
the use of ain't."
Whatever its background, aren't I is indeed the current colloquial
tag ending for the first person singular.
See also Aren't I? (vs.
Am I not?)