Blessed are You, Hashem, our God, King of the Universe, Who chose us from among all the peoples and gave us His Torah. Blessed are You, Hashem, Giver of the Torah.
In chronological order, it would seem more appropriate to initially express gratitude to Hashem for selecting us to receive the Torah and then proceed with the blessing for engaging in Torah study (לעסוק בדברי תורה).
The explanation is that gratitude from someone who comprehends the gift holds greater value than someone who doesn't fully grasp it. Hence, once we delve into the depths of the Torah and appreciate its magnificence, we realize the fortune of being chosen by Hashem and receiving this gift.