From some videos I've looked up, it seems that the original game had a difficulty selection Easy-Normal-Hard.

The remaster seems to have added Hardcore difficulty. I assume the other three (original) difficulties were left untouched? I want to play the game as close to the original as possible so I'm hoping that is the case.

If I remember right Hardcore difficulty is Hard but with much faster enemies and quicker respawning. Kinda like what Nightmare is for DOOM compared to Ultra-Violence. The damage you receive should be the same on both difficulties though.

Hard mode was just fine for me the last time I played through Turok. It had its challenging moments but overall it was always still fair and beatable. I would recommend to check the first level for a few min on Normal and then on Hard and when you know which one does feel better and more entertaining stick with that one.