Akuperma, I’m curious as to your source . Just looking at the NY area, Indian tribes occupied all of Long island and Manhattan Island, so clearly they didn’t avoid the coasts.
Indians also lived on all of the Caribbean islands.
Everywhere the English landed, they encountered indians on the coasts. A special gift that the English and spanish brought did lead to depopulation of the Native American people. Smallpox.
It was the scourge of 17th century Europe and the indians, having never been exposed to it, had no resistance and were devastated.