No premiere date or PV yet. Check out the Crunchyroll article for more information. Synopsis of the source light novels from AniList:
One day, a gamer played video games until he fell asleep…and when he woke up, he found himself in the game world–as a skeleton! Equipped with the powerful weapons and armor of his avatar but stuck with its frightening skeletal appearance, Arc has to find a place for himself in this new, fantastical land. All his hopes for a quiet life are dashed when he crosses paths with a beautiful elven warrior, setting him on a journey full of conflict and adventure.
I mean, it is necessary to show the viewer what kind of world it is, if it is dangerous, etc. It can build up both an empathy for the main character/ characters in the world as well as give a motivation to the main character that doesnt require too much explanation. That kind of start is a rare one, but it can work.
Goblin Slayer, for example, does this to great effect. The first episode is hard to watch, intentionally so, but it easily and quickly builds the basis for the main character doing what he does. It explains to the viewer in no uncertain terms how dangerous such a weak appearing monster is, and why they are a threat. It also shows why the threat is ignored by more prestigious adventurers. And the rest of the anime carries the same dark, gritty tone. I actually quite liked Goblin Slayer.
I just think that Skeleton Knight didn’t really need it because, unlike Goblin Slayer, the entire rest of the show does not match that tone. A lot of people who were put off by Goblin Slayers first episode probably wouldnt have been able to handle the rest of the anime, but with Skeleton Knight I think they might have scared away a large portion of viewers that might have otherwise liked the anime.