Hi doma,
Eostre is said to be derivative of an Indo-European goddess, so I agree there's a credible branching with Eostre and Ishtar back to a common stem. And they certainly look alike as words, which hadn't occurred to me before. That being the case, isn't it delightful that we can get some insight into the things our prehistoric ancestors believed!
Stone Henge. Separate primitive but related religious practices. The pyramids. They show us that early man was tuned into the seasons which told him when to plant and when to harvest and he followed the calendar and the heavens and told stories which were intended to interpret the world. Did the sun worshippers at Stonehenge call Eostre's name as they gathered to worship the dawn during spring each year? Every year, the world renewed itself for them as it does for us. Christ died at Passover and waters the world with his blood and in his resurrection, man is born again. Same root. Same underlying calendar theme.
So the ideas of the early Christian church were somewhat interoperable with those of paganism, even though the links had long been forgotten.
Which takes me back to the Trinity. Perhaps it fit well into Christianity because the underlying template of many religions had a common but long forgotten root.
That's what you are also saying. But you see the whole thing as contrived and I see it as chaotic, in the fractal sense. As the author of Ecclesiastes intoned all those years ago, there is nothing new under the sun.
Or ever the silver cord be loosed or the golden bowl be broken.