Yeah, I wanted to say pretty much what PaulK said. If you just want to use this as an argument against evolution, then it's a bit of special pleading. If, on the other hand, we are going to use your argument generally:
* Then we can't teach
anything in biology, because
all facts in biology are
historically contingent on the origin of life.
* We couldn't teach any chemistry, 'cos we don't know the origin of chemical elements (of course, scientists think that they do, but a creationist such as yourself will dismiss their opinion as "fanciful", since it conflicts with your dogma).
* We can't teach the theory of gravity unless we know the origin of mass.
* We can't teach about electricity unless we know the origin of electrons.
* We can't teach languages until we know the origins of language.
* We can't teach history unless we know the origins of humanity.
* We can't teach geology unless we know the origin of the Earth.
* We can't teach astronomy unless we know the origin of stars.
* We can't teach the germ theory of disease unless we know the origins of germs.
If we can't teach anything until we have an origins story for it that creationists can agree with, then we cannot, in fact, teach pretty much anything, and civilization would collapse within a generation.
I probably needn't mention it but it is my conviction that there is a Creator God, and I for one would object to my child being taught theories that exclude a God and have no plausible beginnings
But I don't hear you making any such general objection. I don't hear
anyone doing so. When your child is taught how stars burn through nuclear fusion, do you actually object to this because (a) God doesn't come into it (b) you don't consider the scientific account of the
origin of stars to be plausible?