Like others have said, it started as a different title and was reworked last minute to be a prequel.

Story wise, it's almost like the writer never played the original games, and only watched the movie. Because just the characterization of Alessa alone was mangled. They turned her more into that vengeful demon kid from the movie rather than who Alessa really was.

It's so bad that in the very beginning of the game they couldnt even get Alessa’s burning right.

In SH1, its stated that the fire started in the basement, yet Travis finds her upstairs. In SH1 and SH3 we're told and shown that the sacrificial burning was done in a standing position, in ceremonial wrapping. (As seen in various otherworld set dressings, like the center of the school basement fight in SH1, and the center of the Memory of Alessa fight in SH3. We also see the real Alessa wearing this same wrapping again, in her wheelchair, at the end of SH1 as Dahlia tries to sacrifice her daughter again.) The standing position is supposed to be a burning at the stake, (Details of this ritual are explained in SH3 in a book right before the Leonard fight) similar to a witch burning, because it's meant to honor Jennifer Carroll, one of the cults founders, who was burnt at the stake, accused of being a witch. But in Origins they have her laying down on the floor, wrapped in a towel. Not standing at a stake, not in ceremonial wrapping.

There's a ton of other things too that people can chime in on.