You said" "Darwin had a completely correct notion of inherited characteristics", which is of course absurd given the fact that Darwin made no distinctions between hereditary variations and a non-hereditary ones. It is a fundamental error that permeates Origin and Descent. And yet you say that Darwin basically got inheritance right.
Darwin's own theory of "particle" inheritance was so absurd, his friends urged him not to publish it. One of the consequences of this theory is that mutilations are hereditary. That's right. It is not Lamarck's theories that predict this, but Darwin's. Oh, the irony.
But the actual 'theory' that Darwin employed in formulating his opinions on evolution was a much simpler one: anything can be assumed to be hereditary if need be.
And yet despite all this, you say "Darwin had a completely correct notion of inherited characteristics", and you probably wonder why you (and many other Darwinians) are rapidly approaching the status of zero credibility.
[allmendream]You understand very little of the theory if you think somatic mutations are involved in evolution.
Darwin certainly thought so, as he made no distinction. How did he know that a tiny variation in beak length would be preserved by natural selection or be "rigidly destroyed"? He must have known that it was a hereditary variation. How did he know that? Because whatever he wanted to be hereditary was hereditary. Why, even "the character of the american people" and "the progress of the United States" were, to Darwin, germinal variations.
You seem to have Darwin confused with Lamarck. Not surprising you seem confused over the entire range of the subject.
Darwin spoke of natural variation within species. The variation within species is not due to somatic mutations, but to genetic variation due to germ-line mutations in the past. Therefore the natural variation within species can and will be passed down undiluted in ‘particles’ of inheritance.
Somatic mutations when they do anything at all cause cancer. Darwin was interested in Inheritance, not Oncology.
Moreover you act as if Darwin had to have everything 100% correct in order for the basics of his theory to be of any use. Science doesn't work that way, but Prophecy and Revelation does. Maybe that is the source of your ample confusion.
There is a tendency to defend Darwin’s errors, because he has become an icon. No one, however, defends Copernicus’s error about the cicularity of plantary orbits. No one defends Newton’s theories about relativity. So obviously Darwin is more than just a scientsist to a lot of people; he’s a kind of god.