The phrases "G-d the Father" and "G-d our Father" are not mentioned in the Tanakh (what is commonly called the "Old Testament").
We know that the Word of G-d was responsible for creating all of Creation (John 1:1-3) and that Messiah is the Word of G-d made flesh (John 1:14).
Ya'akov wrestling with G-d? That was Messiah.
Moshe wrote the Torah at G-d's direction. Messiah says Moshe wrote about Him (John 5:46).
G-d speaking to Moshe at the burning bush (Exodus 3:13-15)?
That was Yeshua, too. Messiah identifies Himself as the "I AM" (John 8:53-58).
Mount Sinai and the giving of the Torah? In Exodus 24:9-11 Moshe, Aharon, Nadav, Avihu, and seventy elders of Israel went up and saw the G-d of Israel. Twice! Once in verse 10 and once in verse 11. Yet Messiah says nobody has seen the Father (John 6:46). So who was it Moshe and the other men saw?
Messiah Yeshua! He is the same yesterday, today, and forever (Hebrews 13:8).