"His Son is the image of the invisible God." By knowing the Son, we learn what God the Father is like. This refers to God the Father. It is best to translate "Father" with the same word that your language uses to refer to a human father.
"God's Son, the most important one over all creation". The expression "firstborn" does not refer to when Jesus was born. Instead, it refers to his position as the eternal Son of God the Father. This refers to Jesus, the Son of God. It is best to translate "Son" with the same word that your language uses to refer to a human son.