We Never Know
No Slack
I agree humans depend on other life/species to survive. Most all life does.Also, setting aside that elevating humans above literally all other life is so abjectly disgusting and abominable it is one of the very few instances where I will use the extreme term of EVIL to describe it...
... humans literally cannot exist without other life. There is no viable hypothetical scenario where that isn't the case. Humans are obligate heterotrophs. They MUST kill other living things to survive. If they don't need to kill others to live, then you are not talking about a human anymore, you are talking about some other life form entirely.
However all life would more than likely be better off without humans.