No, you don't need to learn BASIC before assembly, but many books of the time went that route, e.g.,

https://www.goodreads.com/en/book/show/5011686-apple-machine...

Here is an interesting article on porting a BASIC game for the Apple II to GW BASIC:

https://nanochess.org/akalabeth.html

and it includes a link to the documented source code for Akalabeth (also known as Ultima 0)

Somewhere, there's an article discussing the assembly-language like bit-blitting used to draw the high-res graphics in a timely fashion and the variable/memory management techniques needed to drive that which I'm sure a bit of searching will turn up (or one can derive it from the source).