Were the books of Holy Scripture inspired? Despite the fact that they were written by mere men, both Catholic and Protestant can agree that the Holy Spirit superintended the process to assure the writings' perfection in the case of the 66 books of the Protestant Bible. Catholics would insist that the same supernatural protection of the Holy Spirit was involved in the writing of the Books of the Apocrypha. Since the Catholic Church has not seen fit to canonize the writing of Irenaeus, his writings have to be seen as less inspired than these canonized writings. Valuable for the insight that they provide but not inerrant.
The fact that Irenaeus was only a couple of generations removed from the Apostles and sat under the teaching of Polycarp makes his writings valuable for the insights that they might provide about the practices of the Apostles but it doesn't provide a cloak of inerrancy to his writings. As far as I know, no one with any ecclesiastical authority (Catholic or Protestant) has canonized the writing of Irenaeus. So the working assumption has to be that these are the writings of a mere man and therefore could contain error.
It might be nice for casual readers for you to explain how the books of the New Testament became the NT Bible we have. The importance of having seen the Lord or those directly an Apostle who was with the Lord might be helpful to understand.