The main char has every spell he could possibly want, preserve food? yeah can do, reverse aging? oh yeah, solve infertility, can do, pull out a horde of combat spells never before mentioned despite there being a status in almost every end of the chapter? of course. It kills off all of the tension that could have possibly been because even if they try to paint him as helpless you know he's gonna pull something out of his ass like it was no big deal all along. There's other op main char series where they do create tension, either by a kryptonite or by using the friends or lovers of the main characters as hostages. The main char however doesn't care much about others, several women and ghouls (his allies) were being mercilessly r*ped and he stood by doing nothing. "Oh he couldn't do anything" you say, bullshit, this main char pulls sh*t out of his arse like it's nothing and doesn't even utilize the spells he already has. If he wanted to he could've made an undead army and solved it in two days, but he only ever made three undead, two living armors and a carriage because... he didn't want to bring too many with him? That seems to be the only explanation were given, which is a crappy reason when he's already surrounded by people that knows what he can do, surrounded by plenty of souls and is in a monsters nest where there would presumably be plenty of monsters for his undead to train on. Can he not control more than that? No because he makes numerous small insects as scouts, so he obviously can.

So there's no tension because the main character can just make everything whenever the author wills it, and him already being in possession of several trump cards that he just doesn't use while others are suffering, kinda makes him an a**hole.

Also he's a baby right? At the beginning he can barely keep his head upright, but it seems like the author almost forgets that he's a baby, and at 1 year old he's walking around, talking and cracking nuts. Have the author seen a 1 year old? Maybe he could talk somewhat clumsily, but he's not walking around and cracking nuts, he'd lack the physical strength because of never having used those muscles before and also being a goddamn baby. And people coming onto him, wanting his children, when he's a toddler, that's creepy, that's super duper creepy, I don't think it's being addressed enough because jesus christ that's creepy. At least make him 5 years old, I could swallow the story better if the words i'd expect from the main character was more than go-go-gaga.

(that god eventually manipulate and send people, including his ex-classmates to kill him)

The MC actual age is 16 on earth, 10-20 in 2nd life and 6 or so in 3rd life. Considering his first life was like a country boy who got devoid of technology and social interaction with people and being lock in a cage as a lab rat on his 2nd life. I can understand him for being a wee bit kind and naive but compare to other Isekai with OP naive MC (which are a lot mind you), I take Tsuki ga Michibiku as an example. The MCs are similarly (though Tsukiga MC is younger) naive, OP, have OP companion and striving to create a world of their own in their Isekai world. They MC in Tsukiga pay some what for his nativity and is taught by his companion and also trying himself to learn and improve himself.

He has GOD under him and that god know he is OP so just a question would solve everything but no.

INT to use Mana

His supposed to be "Mating partner" when he grows up, Is get babies for other Ghouls and she already has a baby but she becomes infertile, so he fixes her problem so that she can give more babies from other ghouls. He helps where to get pregnant. She is having s*x every day with other ghouls but it doesn't bother him.