Darwin is that person since he discovered the only universal principle in biology. There is no more universal biological concepts to discover since evolution by natural selection makes universal properties impossible.
And anyway, Darwin's theory has already been expanded on with some discoveries relating to inter-species genetic transfer such as through viral infection and also some interesting insights about mitochondrial ancestry. There is still a lot of mysteries about evolution and there are certain to be unexpected surprises.
Another is that the live is carbon based
Concepts like ecosystem or the nature of predation are also universal.
There is not a single exception known until today by the human race so, do not lie to yourself, those concepts are absolutely universal (right now).
Moreover if any slime or rock was really a early life form we should be able to recognised as that, since many years ago, for sure. A gold necklace that will create more gold or gain mass with time would not have gone unnoticed, neither a limestone rock growing and taking the form of the drawer that contains it.
Finally, an early form of life that did not use RNA/DNA in earth will be contaminated with RNA/DNA of its parasites or symbionts after a few thousands of years. The ecology predict this.