Plot hole: The facehuggers "see" by reading body heat, but this contradicts nearly every other film in which the creatures appear. In the original film they can see Kane's face through a space suit and helmet, so it must be tracking more than just body heat. The creatures also routinely leap directly at their victim's faces. This suggests that they "see" facial detail in some way that goes beyond simply reading body heat. The protagonists should not be completely invisible just by hiding their body heat.
Suggested correction: The thorax and chest cavity is the warmest part of the body. It's tracking the heat from your breath and see's it as an opening down to the chest cavity. Which is why it always latches onto the face. It helps when the victim screams too. More heat.
It can't read Kane's body heat through a space suit, and his breath isn't escaping from his helmet at his mouth. It leaps directly at his face and melts through the helmet to get where it needs to go. The intent in the original film is that the creatures can see, not just read body heat. Additionally, we see from the xenomorph perspective in Alien 3 and Alien Covenant and their vision is not based on body heat. The heroes are invisible here just by raising room temperature.
Where has it ever been stated that they can't read Kane's body heat through a space suit? They're literally showing you it can. That's not a mistake of the movie. Alien 3 happened after this movie. Alien Covenant's praetomorph was created by David. So not the same situation as this. This is also someone speculating based off observation and study vs. A camera trick of showing their actual vision in events that haven't happened yet or on another planet. So they could be wrong.
It's a space suit, they are insulated. That's why when you wear a space suit the lack of atmosphere doesn't kill you. There's no possible way creatures that only see heat could see a human through a space suit. That's a mistake for THIS movie and this movie alone because this is the only instance where heat vision is suggested. The fact that earlier released films take place later in the mythos doesn't really change anything, this film makes a claim unsupported by the other films.
There was wind and ice on that planet. That constitutes an atmosphere. Kane is in a giant helmet, leaning fully over the egg opening as it hatched. That was pretty much the only place it could go. Just because the suit is insulated from the cold atmosphere on the outside, doesn't mean the suit itself can't get hot from the heat inside. Also, these are aliens, I never get trying to apply human logic to a fictional being from another planet, in the future, that survives in an atmosphere we can't.
There is some atmosphere on LV-426, but that is entirely missing the point. The space suit is designed to be worn in no atmosphere, so it is insulated. Space is incredibly cold; if your body heat could be drawn to the surface of a space suit, you would freeze to death in minutes while wearing one in space. You can't read someone's body heat through a space suit. I am not trying to apply "human logic" to an alien; I am saying this film contradicts the others. Thus, it is a plot hole.
You're missing the point. Kane leaned over the opening in a giant helmet, inches from the creature. Where else was the facehugger going to jump to? You keep saying, "you can't read someone's body heat"; that's based off current human knowledge and our abilities, not the abilities of a fictional alien creature who lives in the cold reaches of space. You can't say what it can or cannot do when it is showing you that it can.
We can absolutely say what the creature can and can't do based on what has been shown countless times throughout 40-plus years of canon media. This film makes a claim to create a tense scene. That scene contradicts what we know about the creatures. There has never been any indication that they see based on heat, and implying that they do does not follow how we see them behaving in basically every other appearance. Them "showing us that it can" is the mistake; that's, by definition, a plot hole.
Why do you refuse to answer my question? Kane leaned over the opening in a giant helmet, inches from the creature. Where else was the facehugger going to jump to?
To answer your question: How does it know anything is even there? They see by heat, and the characters in this film are invisible just by raising room temperature. It shouldn't know that Kane is even in the room. So where else should it have jumped? Nowhere; he should be invisible according to this film. It shouldn't have jumped at all.
