Humans can't conceive of large timescales nor large numbers. That's why I use my Rubik's Cube example. A single glass of water contains enough molecules that if they were each a random Rubik's cube then there's a mathematical certainty that 512 of them will be perfectly solved (per glass).

For molecules that are a linear chain of only 2 possible items in the chain, it becomes a 'brute force search' of a 'puzzle space' to find a chain that 'does something like computer code', and the earth has the computing power to solve that brute force problem in 30 seconds, not 30 million years.