Here is another point to drive home in that regard and speaks directly to the two natures of Jesus---the nature of God and the nature of man.
A father---be it of the animal or human species---fathers of the same essence (nature) as he himself is. So if God is Jesus' Father, then Jesus has the nature of His Father. A mother also brings forth a child who is of the same nature as she is. Since Mary is HIs mother, Jesus has the same nature as His mother. The Father is deity, the mother is human. Jesus has two distinct natures, and the two are not mixed together.
Another interesting thing is, that mankind is the only other creation created that bears the image and likeness of God. In that sense man is unique within creation. There is none like us in our finite world. God is unique period. There is none like Him. So how can a finite human stand here on earth, with finite knowledge, finite reasoning capacities, finite vision, and finite understanding, and say to God you cannot be triune?
And because of the above stated, the death of rams and goats and bulls, cannot be a sufficient substitute for the death of sinful man. And Jesus had to be human, to stand in the stead of the human transgressor. And He had to have the royalty, the intrinsic value in Himself to be that substitute. And that is something that is not in a creature, not even the highest of His creation, but can only be in one who is higher than the one being redeemed through that shed blood.