Sam2, I don’t know about that — I did a bit of research and it seems that reincarnation was mentioned in Hindu texts starting around 2600-3000 years ago.
Regardless, though, it still could have come from Judaism, or even from pre-Jewish adherents of the Noahide derech. There is a teaching that Avraham Avinu’s brothers traveled east (which I think is mentioned in R’ Aryeh Kaplan’s book on meditation). So it’s possible all Eastern religions were influenced by Judaism.
The fact that Jainism uses the Hamsa does not prove that they used it before us, or that it’s not an authentically Jewish symbol. Not that it matters — the Hamsa has a long history in Judaism and we don’t need to establish we’re the first or only ones to use it to have Hamsa symbols in our art and jewelry and such.