do you think grammar is necessary for english learning?

Yes it's necessary for learning English.

Grammar is necessary to learn flawless English but we can't speak English only by learning grammar. English learning is all about listening, speaking, reading and writing. Basic topics like tenses, voices, reported speech, parts of speech do help us in learning English but we can't speak English fluently only learning these topics. The only thing we have to do in learning any language is to interact with the people who knows the language very well and observe the sentence formation and try to imitate them. We can learn English by watching English movies and news with subtitles and reading newspapers and story books. Above all, what my suggestion is...to create an environment where you expose to the language much.

It's a backbone of learning English.

yeah

Yes