I think that your examples go to reinforcing rather than refuting St. Thomas' point--he was talking about the same physical universe that Newton was, after all--

In the pool ball example, the pool cue initiates the movement, and the movement of the cue is driven by a hand driven by a mind(The Hand of God!)--the will of the mind being the first cause--so it is a particularly apt example of the idea.

As to validity of our observations, and the models, like cause and effect, that we create, based on them, you are exactly right, they are more reflective of our perspective than of universal truth--St. Thomas was very clear on the idea that our intellect and it's attendent devices had limits--