Well, learning a language is easier at a young age. So it's not an excuse for your mistakes. But, grammar doesn't matter, if this works for you tho. Since you are a kid, you'll not need better grammar skills until you grow up. But don't get me wrong, you have to improve yourself. If you get used to this like that, it's gonna give you a real pain in the ass in the future.
I have no idea how old you are, but this attitude of not improving but standing still, never works. Maybe you don't need grammar to speak English, but when you use advanced grammar properly, the people will think that you're educated.
Why should we learn English abi? We have our own language. We dont need to learn English. We can live our rest of life without English abi. (If i wrong please correct me)
Yes, you are very wrong. English is the globally accepted language, and you're gonna need it even if you don't go out of your house, let alone another city or even another country.