I believe the only extant original documents that predate the early manuscripts of the bible are the Dead Sea Scrolls, which contain much but not all of the Old Testament. Some of these scrolls are in very good condition and others are virtually unreadable.
But to answer your question, no one suggests that early scholars like Jerome were misguided. Most of the criticism is to the effect that the early church was not the Roman Catholic Church (RCC), and when the RCC came on the scene after the time of Constantine it incorporated pagan ideas into its worship and theology and discarded the bible.
That way in a person who holds this positions view, scripture was protected by God and “then” the Church went awry for a 1,000 years finally to be saved by non-Catholics using the bible preserved by the early non-corrupt Catholic Church without tarnish by the corrupt Catholic Church.
Seems pretty far fetched, and historically unsupportable, but at least it’s consistent.
You probably “have to” believe something to this effect in order to be a non-Catholic.
(Well maybe not.) I guess the more charitable non-Catholic could believe that the Catholic Church was/is part of “THE” Church and therefore was protected by the Holy Spirit, at least in regard to scripture, and that it’s doctrinal differences are not any more relevant than the doctrinal differences observed between other non-Catholic belief systems.