Could you elaborate why you consider Zoroastrianism very unsophisticated comparing with Judaism? And what do you mean saying 'its creed is more than a little infantile'?
I posted a link to it; it's self-explanatory. It isn't in near the same league as Judeo-Christianity, but then neither is any other religion or superstition or cult. In fact the 'modern' version of it known today was far more likely to have been influenced by Christianity, not the other way around. The distinct lack of early, pre-Christian era copies of it existing from early sources is evidence it wasn't very popular and not the 'major influence' claimed for it. The modern Persian versions only date from some 200 years after Jesus's time.
They were also enthusiastic killers of Christians along with Jews as well, yet numerous and accurate copies of Christian texts still survived in India and Persia despite the mass murders and centuries of persecutions. The Nestorians in particular managed to survive, and later played the key role in that 'Islamic Golden Age' in Baghdad we keep hearing about from Xian bashing homosexuals and other deviants. If Zoroastrianism was all that big it would be a lot bigger today, and its texts wouldn't have been lost so completely. I suppose there may be a 'Dead Sea Scroll' type of discovery re them in the future sometime, but I seriously doubt it at this point in time, and if it does, it's also a certainty what is found in the stash won't much resemble the modern versions.
The hand wave that conquers burned it and destroyed it doesn't really fly if it was indeed all that widespread and popular; Christianity was far more widely and routinely persecuted over hundreds of years and many copies of its texts are known to exist and from its beginning to boot, also a rarity in history. Compare that to the fact that the oldest known Torah is only about 800 years old.
The language itself is interesting enough; it has a strong Indo-Aryan Germanic influence that seems to originate in in the regions north of the Black Sea, with the Semitic influences coming in much later. The linguistics can be useful in historical forensics, certainly. It's probably a much bastardized cult based on the same roots as Hinduism, with its demon worship obsessions, that migrated west from India. It's the root language of the Iranian dialects and scripts, iirc. Recent ruins in northern Russia point to Aryans originating from there and migrating down to India and the northern Iranian regions.