Not true. The spear wound and crown of thorns are unique. If they aren't 100% unique, then they certainly are uncommon and narrow the range of possibilities substantially.
His treatment was not unique, and therefore, the shroud could belong to any number of individuals that were crucified by the romans...
The Romans crucified plenty of people yet we have one shroud that depicts wounds that are, despite your assertion to the contrary, fairly specific, unique, and match the accounts in the Bible.
It may be proven as coming from the 1st century, but trying to prove that it was Christ's shroud and not someone else's will be a fruitless quest..
Oh, it will never be proven 100%. There will always be room for doubters even if all of the physical details of the shroud pan out as authentic. Of course you can never prove 100% that OJ killed two people, either, unless he confesses.