Evolution does not explain the first lifeform on earth.
Nor will it. Because evolution isn't about where the first lifeform on Earth came from. Stop repeating yourself and pay attention.
If you are saying nothing could be created by some external being, but you cannot explain how the first lifeform arose from non-life, you have not refuted your critics.
Nobody here is saying that something else could not have created life on Earth. The fact of the matter is that we don't know for sure how life came to be. Yet. That's why we're pursuing such theories as abiogenesis and panspermia. We also aren't willing to just accept someone's declaration -
without any evidence whatsoever - that it had to have been designed.
But we are criticizing evolution across the board, not just this aspect.
So what is that, the Royal We? I'm not just making a snarky joke here. Unless you're actually working with other people to criticize evolution, it isn't 'we'. I don't mean just posting their arguments here, I mean actually collaborating with them.
The observation of Irreducible complexity is criticism that lifeforms become increasingly complex over time as the result natural selection on random mutations.
Incorrect. The 'observation' of irreducible complexity is nothing more than an argument from incredulity, a rhetorical and logical fallacy. It is nothing more than someone saying that since they can't imagine any way for something to have existed in a less complex form and still work, that it must have been designed that way, and that no less-complex forms can have existed.
However, this is disproved by the way things are actually designed. Haven't you ever heard of computer program version numbers? Those are successively more complicated versions of computer programs that are nonetheless functional. As you progress backwards and get to the beta and alpha versions, you get programs that are less and less functional, but that are still actually functional. So even if your 'designer' existed, it would have started with something simple and worked forwards to more and more complex stuff. It wouldn't have simply made "eye 1.0", it would have made "eye 0.1.0" and "eye 0.1.1" and "eye 0.1.2", then "eye 0.2.0" and continued working upwards. In other words, this "irreducible complexity" nonsense doesn't even fly in things that
humans actually design. It's just a fallacious attempt to argue against evolution made by people who don't really understand either evolution or design.
It doesn't seem probable that random mutations are going to lead to something of high complexity that even very intelligent scientists could not create with a goal of doing so. That is at least as tough to believe as the existence of God. Are you now prepared to concede that to me?
Until you actually understand how probability works, you have no business complaining because "it doesn't seem probable".
I mean, honestly! You've been criticizing evolution nonstop even though you aren't knowledgeable enough about it to accurately judge whether your criticisms are even valid. And now you're trying to act as if something being improbable means that it can't have happened, which is just flat-out wrong.