No. God is not the first object of our knowledge because the first object of our knowledge in this life is the definable structure of a material thing, which is the proper object of our intellect.
Deus non est primum quod a nobis cognoscitur quia primum quod intelligitur a nobis secundum statum praesentis vitae, est quidditas rei materialis, quae est nostri intellectus obiectum.
The human intellect in the present state of life cannot understand even immaterial created substances; much less can it understand the essence of the uncreated substance.
Intellectus humanus, secundum statum praesentis vitae, non possit intelligere substantias immateriales creatas; multo minus potest intelligere essentiam substantiae increatae.
Rather do we know God through creatures, according to the Apostle (Romans 1:20), "the invisible things of God are clearly seen, being understood by the things that are made".
Sed magis per creaturas in Dei cognitionem pervenimus, secundum illud apostoli ad Rom. I, "invisibilia Dei per ea quae facta sunt, intellecta, conspiciuntur."
Other things than God are known because of God; not as if He were the first known object, but because He is the first cause of our faculty of knowledge.
Propter Deum autem alia cognoscuntur, non sicut propter primum cognitum, sed sicut propter primam cognoscitivae virtutis causam.
We see and judge of all things in the light of the first truth, inasmuch as the light itself of our mind, whether natural or gratuitous, is nothing else than the impression of the first truth upon it, as stated above (Q12, A2).
In luce primae veritatis omnia intelligimus et iudicamus, inquantum ipsum lumen intellectus nostri, sive naturale sive gratuitum, nihil aliud est quam quaedam impressio veritatis primae, ut supra dictum est.