Making declarations is not presenting evidence.
You want to know why some animals are different from others in the way they provide for the next generation? You might alternatively ask why should they all be the same? Once we have a separate species, each species is on its own evolutionary track and nothing makes them stay identical!
Mutations, natural selection, accumulation of beneficial changes over time.
Thank you for likening me to Darwin, that is a high complement, he was a brilliant and influential man.
Why does it matter if Darwin - or me - didn't explain the origin of life? As I see it, there are two possibilities.
a - you think that maybe there isn't any life after all, so evolution can't work because there is no life.
b - you think that by changing the subject to origin of life instead of evolution of life you assert evolution theory is in error.
I lean toward the second idea. Its a common trick of debate. That you have to stoop to debate tricks instead of actual logic and actual evidence does not lend any real credence to your cause.