Xenomorphs are not machine-like in appearance...if you would stop your ranting and take the time to read the thread I linked you, you would have already learned this, and that they very easily could be naturally occuring.
Acidic blood is just a low PH. Nothing more. It's very easy for a creature to attain acidic blood through evolution, especially if its body is resistant to acid.
Poisonous blood is just as far off as acidic blood, and creatures on our planet have that.
Their jaw moves quickly, and is designed to punch through the front of the skull and enter the brain without damaging the life-supporting regions of the brain, such as the medulla and the cerebellum. It's just a perfected tool for quickly seizing live prey, and keeping it alive.
A retractable jaw is just as far off as a set of retractable claws, a proboscis, or tongue.
You still have given no canon proof of how the xenomorphs could have been artificially created.
The edit button is there for a reason, and because this isn't the Chat Topic, you could get warned for spamming.
Forget the freak,
I'm just nature.