If it doesnt make sense I'd be happy to break it down for you.
Are all dogs mammals?
No cats are dogs?
Then no cats are mammals right?
Correct? No there are other possibilties not discussed here. Lewis only presented 3 possibilties. There are other possibilties. Therefore his argument is logically flawed. This doesnt mean his premise is wrong. Jesus could very well have been the son of god inspite of his flawed logic.
So when yes you are correct. Early followers Mighthave corrected errors. They might not have. Since they might not have Lewis didnt present enough possibilties for a logical argument.