Lots of scientists have looked for evidence of multiple origins of life, but so far no evidence has turned up. Every organism found so far fits on a tree of life using a common set of genetic molecules.
It would be an amazing discovery to find a second tree of life though!
I’ve independently had the same question. There are a lot of assumptions in our contemporary cannon that are unchecked (afaik, but open to being told I don’t know what I’m talking about since this is by no means my area of expertise).
It may even be the case that this isn’t possible to know, at least given the evidence at hand. Theories should simply take note of this ambiguity, by qualifying with “if X is the case, that means theory Y is true”
Such a thing would be outmatched in the competition for resources. It's probably much harder for new life to form when there's already existing life around to take whatever materials are required for life to exist.
If life coming to be is already rare enough that we don't see any evidence of it elsewhere in the universe, how much more rare should one expect for it to be under these circumstances?
You don’t know that such a thing would be outcompeted for resources. For example, life may have evolved independently on opposite sides of the earth in quick succession — there would be no competition for resources
It would be an amazing discovery to find a second tree of life though!