TheWonderofYou,
Actually, being a Jew myself I can attest that even we acknowledge that the Passover itself has pagan roots. I mentioned this in another thread: https://www.jehovahs-witness.com/topic/5639150466236416/pagan-origins-memorial-observed-jehovahs-witnesses
True, Adventism has the earmark of being obsessed with ridding itself of anything "pagan," but the truth behind that is that certain forms of Christian theology tend to see our Scriptures as literal Jewish history when we ourselves know that they are not.
The NRMs that were born from the Second Great Awakening rejected many pastors and Christian scholars who had formal training. They often rejected the entire world of academic seminaries as part of "Babylon the Great," leaving themselves with a theology that read the Bible literally.
As a consequence, allegorical narratives in Scripture which seem to give Jewish customs and observances the status of being unique and "comes down from Heaven" are really religious ways we Jews have us to explain our adaptation of the very same. This was misunderstood by these New Religious Movements since they rejected actual religious scholarship.
Passover itself has pagan origins, likely a Spring full-moon festival observed by Abraham's ancestors that was passed on to Israel before they migrated to Egypt. The Exodus has been connected to that time, perhaps historically having occurred on the night of Spring's first full moon, and the feast and its emblems were thus given new meanings.
There was a movement in Judaism around 300 BCE to attribute historicity to the Exodus account, but the original view of it being more allegorical than historical resurfaced and won out. While Jews see no evil or shame in being honest about our celebration's origins, it creates a paradox for those who say pagan culture is a bad thing. This means that Easter and the JW Memorial observance, being based upon our Passover, both have pagan origins too.