Molecules don’t self assemble themselves into a frog, something cause them to. Also, begs the question: when did the molecules first self evolve?
No molecule ever assembled itself into a frog, that's ludicrous.
But simple organic molecules do "complexify" under the right conditions.
And complex chemistry continues to "complexify" so long as conditions favor it.
Is that how life on Earth originated?
Nobody knows for sure, but it's one of several proposed hypotheses.
SkyDancer: "Also, begs the question: when did the molecules first self evolve?"
Nobody knows for sure when or how "complexification" first happened, much less where -- was it even on this planet or somewhere else in the Universe?
Panspermia is the hypothesis that some or all of life's chemistry came to Earth from elsewhere.
But my opinion is the geological record does not support any suggestions of "sudden" or "explosive" advances in life for the Earth's first four billion years.
Plenty of time for what happened to have happened here.