Pay close attention to Hebrews 1:1,2. The one you called "Son" in your trinity wasn't used to communicate with anyone in the past when God was communicating in the past. Rather, only in these last days was the Son used to speak. It's saying that the Son is a prophet used by God to deliver messages through just like the other prophets. This is evidence that the writer of Hebrews doesn't hold the same perspective on God as you do. To the writer of Hebrews, the Son isn't God, but rather the Son is a human prophet, hence he wasn't used for prophecy until after his birth.
Through the rest of the chapter that "Son" is spoken of as an heir (Hebrews 1:2) a representative (Hebrews 1:3) gained a higher rank than angels (Hebrews 1:4) has a birthday (Hebrews 1:5) the Son was procreated (Hebrews 1:6) is a human with a God (Hebrews 1:8,9) and was commanded to take a temporary seat beside YHWH (Hebrews 1:13)
So, in summary, Hebrews 1 is about a glorified and exalted human with a God.