Remarkably means to a degree worth noticing and commenting on. Remarkably similar, remarkably calm, remarkably, he survived.
It is doing what it says: the writer is remarking on the thing, which is why it works before an adjective and at the start of a sentence alike. It is stronger than very and weaker than astonishingly, and it keeps a note of measured surprise.
1adverbremarkablyTo a degree worth noticing and commenting on.
“The old car was in remarkably good condition for its age.”
remarkably is a degree.
French
remarquable
English
remarkable
English, today
remarkably
From remarkable + -ly. remarkable comes from remark + able, from French remarquable.
Etymology from Wiktionary, CC BY-SA