The consequence is you've destroyed a species and set a precedent and for what? One life?

While human life should be preserved whenever possible, there are situations where you must realize that human life is, from the perspective of our role as planetary stewards, cheap and disposable.

Sacrificing some lab animals, even thousands, to cure some obscure but crippling disease that affects a handful of people could be justified.

Wiping out an entire species to save a single person is atrocious, and completely insane.

If you're prepared to wipe out, say, otters to save one person then what's next? Elephants for another? What if it takes two or three species to save someone else. At what point do you stop?

Like would it be acceptable to kill all non-human life to save a single life? There must be some kind of line.

The "no consequence to humans" part is hugely subjective, but a case could be made that we're worse off than our ancestors because of how many species we've obliterated.

It is highly subjective but of utmost importance. Let's say X species of hamster gives no benefit except diversity and there is plenty of hamster species. And let's say wiping it saves 1 person. You would need to consider if this species brings enough hapiness to human to warrant one death.

What I'm trying to say is (like the parents I believe) that the only thing affecting my judgement is humans qnd what the action does to them.

It's still not worth doing. That precedent of removing a species completely starts the ball rolling.

Shit happens, sometimes people die, and while it's unfortunate, it doesn't give us the license to turn one potential death into the extinction of an entire form of life.

Let's turn this around: What if some powerful alien life form had one of their citizens dying but they realized they could cure that individual by harvesting one planet worth of organisms. Given there's billions and billions of planets with life on them, what's the harm in killing Earth to save one of their own, right?

I dont believe we (or aliens) require license for anything that has a net benefit for us/them. It seems morally acceptable (it would, imo, be morally unacceptable to hold animal life higher than the human's, except if they actually provided more value).