there is no time travel at all in the story isn't shown nor even brought up in the parts I've read, but MC power is so absurd I wouldn't discard him being able to do it if he tried, but given how much stuff happens I think the author will not use that gimmick, the change to the world, the loss of blessing, the apocalypse, in a way MC actions made it happen, it was for "the greater good".
The blessings were a system created from the goddess, it made so that humans continued to be faithful, there is a physical tool that grants them randomly, the goddess doesn't appear at all from what I understand, her plan was to only return if necessary.
The blessing makes humans powerful, but even hostile to the demon race, a special human and demon researchers realized it after research, the bad part for humanity was that it made them unable to evolve or work together with the demons, for the goddess it was a useful war for the faith, she didn't think the demons would find a way to study it and use it.
For MC actions the tool stop working, but his power is another thing so he keeps it, when humanity loses theirs, and something happens to the planet/continent following it, I'm not sure it the magic from the tool gone rogue, the special human I talked about had to with it for his body being full of mana (he was a sealed from the goddess as he was against the plan) or humanity simply found themselves unable to do stuff and fight monsters without the blessing.
Alice simply dies, MC never meets her, when she births she destroyes the facility she was in and kills everybody, to do so she forcefully pushed her growth speed, that makes her die very fast, the reason as I told before was that she absorbed all her mother hate against the world and the wish to meet with MC, she is only able to kill the researchers, and she was a monster, not a normal girl, I don't call her a abomination for nothing.
From how the story started and ended in the WN I'm sure the authro had other intentions and screwed up, but not eough to not be granted 2 adaptations, maybe the light novel is better made, but the start is likely the same as the manga is the same as the WN, just faster.
If anyone cares, MC family is annihilated, they were a special noble family in the kingdom, without land but recognized from it, the country armed sword, and they chased power.
MC father in particular, he was a sword saint but wanted to be the sword god, a lost blessing, through his own researchers study or a collaboration with the demons he discovers a way to add a blessing to himself, but as I said is in the blood, and both parties had barely started to understand that stuff, so he tested on the people of the island and then himself, it made the majority die or become monsters, he used the remains of the ancestor of the family that was a sword god and was barely able to keep a human form, then started to kill everybody to test the power, he even killed the king to make the nation go to war with him as he had no one strong enough to fight and give a challenge.
MC goes on a expedition to kill the rebel island, he spams the sword god blessing on a team of people and sends them to kill him, to destroy his morale, what he sought all his life was easily achieved from his discared son, and he got defeated from people that weren't even fighters.
The fiancee that insulted MC wasn't compatible with the grafting and became a monster, barely able to keep her sanity, but becoming a monster she just wanted to die or return human, she reaches the arena of the fight after MC father is defeated, MC doesn't have the time to do anything, unclear if he would have, she is killed from his father that hopes to gain more power from eating her flesh and adding that blessing, he just becomes a monster and is quickly put down.
