I think it would be great to clarify and say that
Amit is a modern Hebrew name which was created in modern
Israel.
But I think you don't know much about the Jewish community in the USA if you think that modern Israeli names have not been adopted here. There are quite a few American Jewish children who have been given modern Israeli names such as
Lior, Tali, and
Aviva. Jews in the United States often pay attention to Israeli culture and have some knowledge of names being used there. So it's certainly not impossible that there has been a Jewish child in the USA named
Amit.