Either that process has random elements or it does not.
If it does, then the randomness (which is not will) Is the part that varies the outcome. If it does not then the outcome is entirely the result of the conditions.
"unnecessary" is a nonsensical word. Something cannot be absolutely necessary... it can only be relatively necessary.
The brain has developed the way it has because the developments were beneficial to the likelihood of reproduction.
A tautological assertion is self-referencially true. Sometimes referred to as a "truism".
My claim on free will "It either has random elements or does not", or the inverse "It is either determined by the state of everything or it is not", is a tautology.
That is only relevant to the definition of free will you use, used by the philosophy of determinism. It seems obvious to me that a human being has a lot more complexity then the philosophy allows for. However the definition, though a bit ambiguous, is what it is. The discussion so far is if there is a disagreement about "free will", refer to the definition.
So, the definition of free will according to determinism is is self-referencially true.
It's not what I'd call free will and I suppose you wouldn't call it that either since it refers to something which according to the claim doesn't exist. Kind of a odd discussion but whatever.