Well, I honestly don't think anything can be consider "canon", not even LOTR and the
Hobbit.
We already have the example on how
Tolkien changed the story on how
Bilbo got
the ring.
Tolkien never could make up his mind in many topics. The only reason why LOTR got to a final form was because to pressure from the editors. I don't think Tolkien was completely satisfied with everything.
Yet, we need to have something to follow, and in that sense I don't believe we can ignore
the Silmarillion.
Simply put, without the Silmarillion, LOTR doesn't make much sense as a full story, there are so many things based on past
ages, even the appendices are not enough, like what are the
Valar, what are the
elves for that matter?
It's true that the final version of the Silmarillion was compiled by CT, not JRRT, but he did an amazing job finding the stories and putting them together.
The History of Middle Earth shows how that process worked, and I don't believe that anyone knew JRRT's work as well as CT.
I see it as a collection of myths, some based on reality of what really happened, some not, and it's up to us to decide which of those myths we consider real, not forgetting that absolutely nothing that is written in Tolkien's world actually happened, it's a fantasy but it does have its boundaries, within it there is some logic but it can be interpreted in different ways.