Thomas Aquinas dealt in the analysis of what things are – the subject matter of science and philosophy. Aquinas’ quest was for the reasons for things. In the Christian tradition even the mysteries of faith are not irrational in themselves, but often beyond human grasp unless the meaning is revealed by God to his chosen.
In philosophy Thomas Aquinas sided with Aristotle most of the time, but greatly expanded his ideas, joining them with the ideas of St Augustine. The Greek philosophers were firm believers in God, but Thomas Aquinas took this further and Christianized the ideas.
Aquinas established that creatures, including human beings, have agency and are separate to God. The purposes of creation, however, are drawn towards their conclusion by God’s providence and governance of creatures.
Aquinas proclaimed the God of an ordered universe in which each thing has its place. He likewise ordered his writings such that they could be read – which was unusual in his day. Many ancient books read like a hotchpotch of bits and pieces.
On the question of origins, however, Thomas Aquinas was bound by the science of his historical time period – the High Middle Ages. He could not know what was not available to know. He could not know what we know now with the benefit of modern science. I think that he knew that he couldn’t know because in discussing origins and addressing certain questions, he does not say categorically that it was like this or like that. In these cases Aquinas quotes all the sources and opinions of the erudite of his day without declaring which one should be followed or taken as the definitive true path.
While displaying an openness of approach on questions he could not answer, he was very firm on the truth he could establish. His arguments are built up step by step paying attention to detail. He details the way in which the Bible was written and the particular words used, the intention behind the text, and makes observations relating to the human condition.
There have been many centuries of exegesis of the Bible by theologians; among all exegets, I believe that Thomas Aquinas is among the greatest.