a series of dividing by zero and a trillion chances to one for just the right conditions to happen to just the right thing to spontaneously result in the first life form
On the contrary, we don't have any idea what the odds were. They might have been 0.001%, or 50%, or 1 in a trillion. It's entirely possible that the laws of the universe tend towards complexity and that complexity tends towards life in such a way that the odds were 100% over the long-term (similar to how convergent evolution produces the same features multiple times in nature and how intelligent apes seem to have arisen multiple times before Homo sapiens).
Yes, one could still say, "Well what are the odds the universe would turn out that way, with rules that result in intelligent life?" Hopefully I don't sound like a broken record when I say that we don't know how many universes have existed before this one. If the odds of us developing were one in a trillion, but we are living in the trillion-and-first universe, and the previous trillion did not have life, then the odds were well in our favor.
There's simply too much we don't know. That doesn't mean that anyone is discarding any possibilities. You are unlikely to think of anything that a scientist hasn't already. We're still learning a lot about our universe, so as our knowledge increases, the data will lead to hypotheses, and then theories. You are skipping a couple steps by going straight to, "We're robots made by aliens." It's a fine premise for a what-if discussion, but it's not testable so it doesn't have any scientific value.