Why can I now read a book of starter level?

One year ago I couldn't read a readers book of starter level. Those days I read over ten books of lower than starter level on "Tadoku no Mori" of a service for readers while using dictionaries.

The books I now read are in starter level. One year ago I absolutely couldn't read them. Because there are a lot of easy words on them, I probably could have read them using dictionaries.
But not.

I think to have had wrong or a lack of my English Grammar. It seems the Grammar and several unlearned words or phrases allowed to strangely understood sentences, so in confusion I wasn't able to keep reading them.

Why can I now read a book of starter level?
That's because I have learned Grammar enough, I thought.

The minimum not-confusing Grammar for starter level is essential.
Maybe my minimum line would have been too high though, I would have lacked the imagination at that time.