Hi,
This happens when you use multiple content types in your list/library.
Some fields fall under one and some on another.
However at the top of the newform.aspx you will find a drop down as Type where you can switch between these content types and can provide values to required fields.
In an alternate way you can disable content type and then you can create your columns. In this case you will be able to see all of them in newform.aspx .
I hope this will help you out.
Thanks,
Rahul Rashu