It does not matter if aspects of kabbalah like reincarnation, exist in other mystical philosophies, such as hinduism.
It's a concept that is very natural to ones imagination, just as the soul is. So similarly, just because some other people has dreamt up the idea of a soul, does not mean that the soul does not exist.
Furthermore, if there are complex subjects that are shared, that can be explained too..
We used to have schools of prophecy, lots and lots of prophets.
The book of prophets only mentions those whose prophecies are relevant to us today. We have had far more than the (often counted as) 48 prophets and 7 prophetesses mentioned in tenach.
According to what I read from not such a great source - the koshertorah site.
Rabbi Dovid Ben HaRAMBAM , a kabbalist/mystic, met Sufis(a bunch of arab mystics with a very generic philosophy far older than islam, that ended up islamizing their philosophy, probably to stay safe, and now most of them consider themselves muslims).
He believed that the sufis had met with and learnt something from the ancient israelite prophets that wondered around the deserts.
Also, in the so-called golden age of spain, it is possible that mystics of various religions mixed and influenced each other. This would have corrupted kabbalah, and kabbalised the mystic streams of other religions.
Also, I heard from an interview tamar yonah gave to Gutman Locks, (a secular jew that became a hindu/buddist guru in india, then returned to orthodox judaism).
The verse in Genesis that says Avraham gave gifts to the sons of the concubines. Rashi quotes a tradition that shose gifts were special names that had certain powers. There is a discussion in the gemara, that these powers are treif (not kosher) for jews to use, but ok for non-jews.
And in that section where it names children of avraham's second wife Keturah, it says them or some of them went East (this could be the india area), and it mentions their names.. some of the names are indian sounding.
One of them is called Ashram, which apparently has many scratching their heads, but one commentator says it means Tent. That is exactly what it means in hindi/the indian language.
This Gutman Locks, suspects that the name brahminism comes from abraham.
I would not look at that as facts.. the point is you can keep an open mind, and realise the picture is alot bigger than it might appear.
It is also possible that much or even all of kabbalah is wrong. Other than that which is in the talmud, that which the RAMBAM mentioned. It does not matter that much. Kabbalah is not fundamental to judaism. It looks as itself as fundamental, and it discusses the mystical side of the fundamentals, but the fundamentals exist without it.
Just saying Oh, reincarnation exists in hinduism.. Is just irrelevant.
And also, according to "lulab", reincarnation in judaism is not of soul, but of mission.