I think the writer of Hebrews is using this word as a 'biological relationship',biological in the sense that they are One, not in the human context, in vs 5 he quotes Psa 2:7 "you are my Son today I have become your father." In Mt 3:17 at Jesus Baptism and again in Mt 17:5 at His transfiguration God Himself spoke and said " This is my Son, whom I love; with him I am well pleased". The writer knew the relationship between Jesus and his Father, The triune God. John 17 Jesus prayed to God
in v1 He says "Glorify your Son, that your Son may glorify you." Jesus Himself said here and a number of times that God was his Father, and in v5 He Prays "Father, glorify me in your presence with the glory I had with you before the world began."
The Son's words would have more weight than the prophets, because the prophets were men, they were humans just like you and me, interceded between God and man. They still sinned and made mistakes just like another man.
Jesus on the other hand was sent by God not called, he is sinless although he faced every sin, He is the creator of everything (Jn 1:3) Jesus was with God before the beginning of the world. It's not just a son that is the issue, it's God's very own Son.
Jn 1:1 "In the beginning was the Word, and the Word was with God, and the Word was God."
In a sense if Jesus and God are One in effect, then you could say that Jesus 'The Son' called the prophets, Giving Jesus more weight than the prophets who were his voice