Of course Samuel is a human, no debating that, but he has some "superhuman" feats, almost comic book heroes type of feats. So although he is a human, there is something very suspicious about him.
His strongest feats
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-Ripping a door off it's hinges
-Lifting Ulthor Young by his hair with no stress
-Beheading Nestor Nik with one cut of his sword
-Lifting up a limp, dead horse
1.First of all we see Samuel's incredible strength when he rips the door clean off, during his fight
with Nestor and Ulthor early on in the book. 'Without warning Samuel jumped into Ulthor’s door ripping it straight off its hinges', Aeyron when he arrives to the scene notices the missing door and comments on it-'...walked out studying the broken door. Very strange.'
It's clear that Samuel tearing the door off was an uncommon sight and something not an ordinary man could do. Samuel even reflects to himself that he isn't normal. 'If i were normal that wouldve killed me'
2. That brings me on to something that also happened in the same chapter when Samuel pulls up Ulthor by his hair WITH HIS WEAK HAND. 'Samuel grabbed him by his hair and lifted him up with his left hand.' He shows no effort while lifiting him, no pain or no struggle, he picks him like it was nothing. After the fight with Nestor he stares back at Ulthor and reflects- 'had I done that to him? ', this shows that perhaps he doesn't realise how strong he is and these things he does is just casual, which is very strange that he thinks this behaviour is normal and isn't shocked by it.
3.Now. Beheading someone isn't that easy. Ofcourse it's somewhat made easier in my books but that's besides the point. In real life an executioner would take several hits to do the deed, the only other execution(to my memory) in the book is when Jax Storm executes Farlan Penny and he does it with his axe, a weapon built for cleaving and digging through flesh. Samuel on the other hand has a sword and cuts through Nestor's helmet. Now, Samuel does have a Celtigan Steel sword-the sharpest in all of world but he still needs power to cut through steel, possible chainmail, flesh and then bone. That in itself takes incredible strength and just goes to show Samuel's strength. 'Nestor’s helmet went spiralling and so did his head which had fallen out of his helmet. Both splashed into the river and Samuel stood over Nestor’s decapitated body. He had cut his head clean off his shoulders. His Celtigan Steel was sharp enough to cut through even Nestor’s armour.'
4.Not even a minute after that Samuel lifts a dead horse to relieve Wendel Cross. Although he struggles in this part-'With superhuman strength Samuel lifted the horse and began to move it, his arms shaking under the weight of the horse, he partially moved it before he let go from exhaustion.' he still manages to lift the hrose and pull out Wendel Cross. Horses on average can weigh 350-1000kg, a warhorse would weigh at the top end of that if not much more. Wendel Cross who is an enormous man, 7'4'', 'struggled to break free' under the horse. The strength that Samuel has IS NOT NORMAL.
In conclusion Samuel's Kratos-like-strength is definitley not an inconsistency, its been mentioned too many times and in too many important moments, often following up from each other. Samuel 100% has giants blood in him or he has had some modifications to his strength factor. Perhaps he's an mutant or meta human like the X MEN because there is no way he can be normal and be this impossibly strong.