What was the original plan?

The history of Arda didn't go according to plan. Eru's original vision was marred by Melkor. The Elves didn't all simply go to and remain in Valinor.

Do we have any sense of what Eru's original plan was, if Melkor hadn't rebelled? Some kind of Garden of Eden-like blissful existence for all time? Elves would have woken up and been allowed to stay in the East and multiply?

One could probably argue that Melkor's rebellion was, in some fashion, part of the plan, though, bringing even richer music to creation. So let's allow that up to the Elves waking up was still in some sense part of the original plan.

From that point forward, what was the original plan for Elves and Men? Elves would have all gone to Valinor and stayed there, having their own little Garden of Eden, never interacting with the rest of creation?

And Middle-Earth stays for Men to populate and live as they see fit? It seems like the development of Men would have gone very differently (i.e., poorly) without guidance from and interbreeding with Elves, though. No Numenor, no Dunedain. Just...Men.

EDIT: Maybe "plan" isn't the right word, since Eru's plan is a tautology: it is logically impossible to do anything outside of Eru's plan because that plan also encompasses everything "bad", "unintended", what have you. I'm more curious about what the counterfactual history looks like, one in which Melkor didn't rebel, or all Elves went to Valinor and stayed there.