Science has been unable to establish what life came from ergo we do not know. That does not mean abiogenesis is fact, it means that we do not know.
But we do know a few things. We know there was once no life, then there was. So, we know life formed. And that's all we need to know in order to know that abiogensis is a fact. Life formed by some sort of process that follows all the same laws as every other process. Star formation, volcano formation, hurricane formation.... And formation of life. "Abiogensis" is just the name given the process. It's not any less a fact than is hurricane formation. "Hurrigenesis"...
That is the most likely but is not all encompassing.
Life may have been seeded by another form of life. Life may have come from an extra solar meteorite. Perhaps there are extra dimensional beings involved and of course there is always the god did it excuse.
Each may be more unlikely than the last and certainly not a complete list but that does not equate to us KNOWING anything. It strongly suggests such but that is not the same thing as a fact. Abiogenesis is still a guess because science has been unable to establish any real framework as to how it works. We do not even understand what original life looked like as it is now believed that DNA was not the starting point of life.
The same thing goes for humans being nothing but deterministic systems, another claim of hard fact that you made. While I ascribe to both Abiogenesis and determinism as physics strongly points to that direction there is still absolutely zero understanding of what consciousness is or how it arises strictly from deterministic systems. Science is very specific here and that is what makes it so damn effective - the answer I do not know is an acceptable one and the fact is that we do not know if either of those contention are, indeed, accurate. The problem that arises with religions views often times is the assertion that it is known, God did it and that is that. Science does not need to go down that same silly road. We do not know if life arose form non life and we do not know that we are strictly deterministic machines. Physics has shown that those are both extremely likely and scientists are working to prove those two hypotheses right now. Abiogenesis has proven to be very difficult as we do not even understand what original form life may have taken on. Consciousness is currently beyond our grasp as we have no understanding there but current research into AI may very well shed some light in that arena.
