Jesus was what? A heavenly spirit-creature ( Pr. 8,22, Re 3,14: Jehovah himself produced me as the beginning of his way, the beginning of the creation by God). Jehovah did not use preexistent material.
Jehovah was what? A spirit creature and he doesn not need material energy. He is spirit and uses spirit to create.
This kind of divine spirit, the basis of gods creation, does not need any energy out from material universe to create heavenly persons. It was a creation process simply in "spiritual realm" where Jehovah exists and dwells. This also because it happened before the creation of the material universe.
And as the material universe was created by "active force" , spirit, ru'ach , which was moving over the surface of the waters, Ge,1,2 , this demonstrates how the heavenly spiritual realm and persons were also created by "active force" out of gods mouth.
So Jesus would be a spiritual "WHAT", a heavenly something, but not a material "WHAT". These are two separated spheres in which God is able to create creatures. here and there. When the word once got flesh and God turned Michael into Jesus the spiritual what got material what and this to an extent of 100%. The spiritual what changed to material what and back. A mixture of both is not possible. Either spirit person or man.
This would be my answer if I would be apologist of JW. I hope I didnt misinterpret any JW or intervene into personal agenda. I have no evidence except the watchtowers that taught me to think so.
One could however looking over this credo can also say that the pre-existing Jesus was never a "material" fact, but only a "spiritual" idea. Like a fantasy creature.An idea that evolved because Jesus was seen close to God, that they didnot see and difference any more between the material what and the spiritual what. A spiritual reality that must have existed ever alongside God. Their Jesus got then the middlesman between the spiritual realm and the visible world. The Jesus became Christ.