There was NO closed canon until Trent.. prior to that different countries had declared different books as canonical at various local councils ..there was no agreement on all the books until Trent
The canon, by definition, was the list of books accepted universally by the Church as books that were read publicly in the liturgy.
While Trent did the work of actually defining the full list, the Council's list was not drawn out of thin air, but from the immemorial practice of the Church.
In the Catholic sense of Scripture, Scripture as publicly proclaimed in worship is absolutely central - as opposed the the central place of Scripture in Protestantism as private devotional reading.
This does not mean that Protestants do not publicly read the Scriptures in their liturgies or that Catholics do not privately study them. It is a matter of emphasis.