It is one thing to claim the trinity was a Catholic invention. But another to prove the statement from the facts.
For one thing, when christian Missionaries first went to India in the 16th cent. they found Christians already believing that who claimed to have been preached to by ST Thomas.
Catholic simply means 'including a wide variety of things', or 'including all christians' or historically to the doctrines and teaching of the Western Church.
Since in this last sense the Catholic church did not even exist in the 2nd century where many church Fathers are already declaring a belief in the deity of Christ it is a false statement. After the orthodox and western churches split, the trinity was taken by both. And the Orthodox Greek church is older in tradition than that of Rome. Both believe in the divinity of Christ.
Throughout the history of the western church, doctrine only came to be codified and explained when some heresy was causing a stir.
If either doctrine was as clear as WBTS claims there would never have needed to be a council in Nicea. In any event the vote was almost too close to call. Whatever one believes about Jesus' nature, the bible does say that there is no other name under heaven, and that he should be worshipped.
Polycarp is branded heretic by the 2nd cent church fathers, though he is championed in the WT for denouncing the trinity and immortality of the soul.
It is rumored that the trinitarian bishops had the leading opponent poisoned, but that does not of itself make the teaching untrue. It Just shows there were men back there who were as unscrupulous as the Borg.
The WT argues that so many cultures believe in a global flood, so it must be true. It doesn't suit them to use the same logic in this case.
If your reasoning is based on the "Trinity" brochure there is a very good discussion of its misquotes and misrepresentation of sources online. (I think it is actually a Catholic apologist site)