Wrong. People didn't write the Torah at all. G-d wrote it (according to a midrash, "974 generations" before the Creation). G-d then dictated these words to Moses, letter-for-letter. This is the immemorial Sinaitic Tradition which you pseudo-traditionalist Catholics reject because a bunch of late nineteenth century German atheists came up with theories to discredit it.
Everything has to be "interpreted," not just the first eleven chapters of Genesis. That Catholics choose to interpret one thing literally and another non-literally merely shows their hypocrisy to the entire world.
You are also ignoring the fact that it isn't just the "hexameron" that Catholics reject, but the entire first eleven chapters of Genesis: Cain and Abel, Metushelach, Noach's Flood, the Tower of Babel--everything. According to Catholics and liberal Protestants, when one comes to Genesis 12 suddenly mythology morphs into history.
What G-d said is true, whether or not anyone else was there to confirm it. You don't think G-d is trustworthy?
I think Catholics cling to a literal interpretation of the "words of institution" only because it ticks Fundamentalist Protestants off rather than out of any principal. And it seems to me more and more that this is so.
You don't seem to understand that even if one doesn't take the story of Creation absolutely literally, that is, its occurrence over 6 HUMAN days, one COULD believe quite strongly that God created all that is in the Universe. We believe He is Lord of all, that He brought about many signs and wonders in the Ancient world, and even if all of them didn't happen exactly as it is written in the Bible, since many were described later, by people who received the stories many generations removed, they were inspired by the Holy Spirit, and written to teach the lessons that God wants us to know. And finally, that He loved us so much, even after we'd turned away from Him many times, sent Jesus to be our Redeemer.