Given how this “shaman” called alchemists “copycats”, I’d be willing to bet that they are someone who uses Primordial Magic since it was explained in previous chapters that there was a connection between it and alchemy.
They also didn’t like being called a “Shaman”, so I bet they are something more along the lines of a “Magician”, “Sorcerer”, or “Spiritualist”.
I don’t think I’d call them a Demon, as it seems like the “Shaman” recognized something about the summoned beast Rizalham used and so pushed Rizalham to the point where he turned into a demon. And the “Shaman” didn’t seem to do it because he thought it was an honor, because the “Shaman” was actually really pissed at Rizalham for failing with the weapons he had ordered.
As for the “Shaman” thinking that they are stronger than alchemists, they might not actually be totally incorrect. Rust was one of a select few of “Master Alchemists”, and we have yet to see what happens when one Master Alchemist fights another. Rizalham ran away after creating a distraction, but Rust was pretty clear about how a full-on battle could permanently devastate the area.
We’ve also seen that other lower-ranked alchemists have been in awe of just what Rust is able to do. If the “Shaman” has only been dealing with lower-ranked alchemists, then it’s absolutely possible that they ARE stronger than the vast majority of alchemists.
Well, all I see, is every shaman's trick getting curb-stomped by MC.
His familiars? All they have is weak poison, and they can't even survive getting stomped by a hippo. They aren't even good at flying. He uses them like they're disposable, but they take so much time to make, MC probably can make a full-strength alchemical beast in that time.
His plans? Depend on getting weapons from alchemists.
His command of destiny? None, all shaman's plans are ruined by sheer coincidence. Even MC's absence ruins shaman's plans.
His biggest success? Recruiting a master alchemist (Rizalham) to his cause. And that was only possible because Rizalham messed up and did not properly remove a monster from his body before consuming a lot of healing potions.
Primordial Magic? More like, playing with toys left to him by ancient civilizations.
But shaman's biggest weakness is that he is Evil(tm). He does not improve the world or research anything, he only causes harm. And so, he is doomed to become obsolete someday.