actually your science textbook would tell you that scientists do not know for a fact how the universe and life on earth began, that there are just theories, some more plausible than others, but all with their supporters and detractors, and with all cosmological theories there are still discoveries that seem to contradict or not fit in with what we know or think we know.
True, but nobody in science claims ultimate knowledge in any subject. Science is not a proving process, it is a falsifying process. Nothing is proven in science beyond predictions made by a theory and theories are revised due to new evidence.
That being said, does this mean that the process explained in a theory is false? No. A theory is an explanation of how and why something happens, the phenomena itself is not judged by the validity of the theory. Just because the theories are in dispute does not mean that scientists disagree that the phenomena happened or is happening, merely that they disagree with the explanation.
When it comes to the gravitational singularity, the discussion is much more about the origins. That’s when you get 11 dimension m-theory, loop quantum gravity, and so on and so forth. They disagree in the explanations, but they don’t disagree with the gravitational singularity. You see where I’m going with this?
I specify the term abiogenesis in my explanation because that is the title given to the theory of the origins of life and it is a developing theory. That being said, it’s hard to deny when we already have empirical proof that some organic material can be synthesized via inorganic material (such as amino acids formed in the Miller-Urey experiment, the nucleotides formed in the meteorite recently found by NASA and so on and so forth).
We may not have a unified theory, but we have evidence and from that evidence there are certain things in which we can conclude and agree on that happened.