Angelomorphic Christology in Acts 7

God "spoke" to us "through/by" many intermediaries: prophets, angels, and Jesus. Jesus is better than the other two. That's the point of Hebrews. I believe that the writer of Hebrews holds a tradition that the Son (as spokeperson in behalf of the Father) was better than the prophets and angels, both who were also carrying the function of being spokepersons. This didn't nullify the other tradition that the angel of Yhwh was the pre-incarnate Word, the Son of God, Jesus Christ.

The word "angel" in English is typically referring to a heavenly being. But the Greek word it translates (ανγγελος) is used to many non-heavenly beings (human beings "sent" by God to accomplish his will. When referring to these, it can be translated as "messenger" which has less connotations of being a heavenly being as known in the English speaking world. The word "'messenger" of course can translate it regardless of the essence of the one sent [1]) in the Greek Septuagint and the Greek New Testament. That is, the word ανγγελος does not denote essence, but function. Either heavenly or earthly beings are called that. So regardless of one's essence, if one is sent from God, he could be called ανγγελος. Thus, it is apt to call Jesus (the Word himself) ανγγελος because the Bible does refer to Jesus as one who is sent by God. In the 2nd century A.D., Justin Martyr called Jesus an ανγγελος while believing that Jesus was begotten "before all creatures".

The context affirms that the angel in Acts 7:32 was the Lord Jesus Christ himself:

Acts 7:30-33, 7:59-60 (NRSV):

30 “Now when forty years had passed, an angel appeared to him in the wilderness of Mount Sinai, in the flame of a burning bush. 31 When Moses saw it, he was amazed at the sight; and as he approached to look, there came the voice of the Lord: 32 ‘I am the God of your ancestors, the God of Abraham, Isaac, and Jacob.’ Moses began to tremble and did not dare to look. 33 Then the Lord said to him, ‘Take off the sandals from your feet, for the place where you are standing is holy ground.  59 While they were stoning Stephen, he prayed, “Lord Jesus, receive my spirit.” 60 Then he knelt down and cried out in a loud voice, “Lord, do not hold this sin against them.” When he had said this, he died. 

Notes

[1] How does "angels" typically used in scripture? Young's Literal Translation translated it as "messenger" in Hebrews 2:7. The English words "angel" and "messenger" equally literal translation of the word "anggelos". In English translations, if the translator chose "messenger" but it refers to heavenly beings, the translator specify it: "heavenly messenger". We cannot get "heavenly messenger" from the word ανγγελος alone, as the word does not connote essence, the English does, the Greek doesn't. One who is ''sent'' to be speak the words of God to the people in behalf of God is a ''messenger'' ( a spokeperson). A messenger could either be heavenly being or a human being.