It seemed like the sage was human when Jiraya was talking about him. Plot changed and now he's a god.
Naruto and Sasuke is basically half the sage, the sage and his brother took out kaguya right. The power difference makes no sense. Naruto and Sasuke is too close in power to the two brothers despite being half a brother in power.
It was known for a long time he was insanely powerful. Nagato mentioned his rinnegan techniques were crap compared to the Rikudo and he sealed the Juubi which at the time was the strongest thing around.
The sage didn't have the tailed beast powers like naruto, so thats the difference. Hagoromo also didn't have the sharingan or any of its techniques as far as we know.
Different techniques in a similar situation. We also have no clue what kind of powers Hamura had, so you can't compare him to sasuke or naruto yet.