You should read On the Origin of Species. He handled all your objections there.
Spoiler warning: Darwin didn't really have any problems with the eye. That's just something creationists say.
Spoiler warning: Darwin didn't really have any problems with the eye. That's just something creationists say.
Darwin's understanding of e.g. Heredity via Pangenesis turned out to be wrong, so it is not like just holding up a copy of 'On the Origin of Species' as the final judge of "origin reasoning" will take use very far.
The mechanism wasn't understood at the time yea. That's not really relevant, and not really covered in Origin of Species anyway.