Ah, I see what you are saying. From Chapter 2 it looks like the fixed values are: Blessing None, Health 30/30, Mana 10/10, Physical Attack 10, Magic Attack 10.
Yeah... it does sound like this makes him invincible. His health is fixed at 30/30.
His mana is fixed at 10/10 MP. Since his level is locked at level 1 this can't be increased. This means he can use any spell that uses 10MP or less only.
To do powerful attacks he creates large pools of mana by layering 10 MP attacks in quick succession, converts the pool to have an attribute...
And they might do it again. There is a webtoon version on Piccoma (https://piccoma.com/web/product/135714) (Japanese IP address required to visit and Japanese phone number required to create an account to view past chapter 3) but it seems to be up to chapter 21 of this manga.
There is a...