Sorry to impose logic into the argument. You don’t have to “buy” it. The facts are what they are.
In not all, but many of the cases the bones are found they are fossilized somewhat intact. Humans may not be perfect, but the human mind can work a jigsaw puzzle. You’re suggesting that maybe these bones were scattered about and found laying loose maybe miles away and some conspiratorial archaeologists decided to glue them together to fool a bunch of mindless morons. No. They save that for the prehistoric men.
Now, the skin and scales and fatty tissue and the like... purely our imagination.
And could they (early man) have assumed these bones came from monsters? Sure! But the order the bones were put together would have been a totally different animal than we would have put together with present technology.
Leaves too much to the imagination to come to the conclusions you’ve reached.
OK then, doesn't that prove my case? People 3,000 years ago found these fossils, too.