Not for nothing, but saying "no plagiarism and no theft" isn't going to deter anybody looking to do that, and it's generally understood that it's not okay to do those things in the first place.
As for the script itself... I have no experience reading screenplays or anything like that (technically it's something for a manga, but the concept seems the same) so I can't comment on the structure. However, I noticed some spelling and grammatical issues throughout the dialog in the early pages. And two of the characters ("the ugly man" and the "strange man") speak very strangely, particularly when it comes to over-explaining things in dialog (iirc, there's a mention that they'll cut off peoples' faces to prove that they're dead, which doesn't even work well because the bone structure underneath the skin is what gives the face a lot of its appearance. And it's a lot more to work to cut off a face than to just take the whole head... but, if you *really* wanted to be practical, you'd just take photos of the body).
Just from what little I read, it seems like it needs a lot of work, and much of that probably needs to be handled on your side before you start to get opinions on it. Best of luck on the project, though.
