Coel says "Creationism is simply the belief that God created humans in something like their present form. For the vast majority of the history of the Catholic church that is what the vast majority of Catholics (and other Christians) believed."

No it isn't! You ought to look up what the fundamentalists believe it to be; in its pure form it is that all life was created by God, not just humans. There is no such thing as evolution in their book and, moreover, the vast majority believe the world to be 6,000 years old. Methinks you're defining creationism for your own purposes.

As far as I know, the RCC dropped belief in a young earth before Darwin published I dunno when it dropped what you claim to be creationism, if it ever believed it in the first place. Gregor Mendel had n problem undertaking his research and publishing it.

I assume (and could stand corrected) that the RCC's position on evolution was ambiguous when Hitler was in his youth. The position nowadays is that humans are the product of evolution but that God changed humans at some unspecified time by giving them souls.

The creationist movement has its origins in the 19th Century amongst Seventh Day Adventists; since then the RCC has been almost entirely absent from the creationist movement. The only British Catholic creationist I can recall is GK Chesterton and he is long dead and was almost certainly an old earth creationist.