you are a part of this world . your goal is learning . no one can stop you . you can do everything to achieve your goal . what they said on you is not important because when you don't care about their speech you will find your self at the end with a great English level.

finally don't miss that everyone makes mistakes & the mistake is the beginning of success .

best wishes to you .

Often I get messages from strangers and all they say is "Hi". Nothing else. So I think you have a written a nice, clear introduction, and in my opinion the other people are being discourteous not replying to you, I assume you are only contacting people learning Japanese. Also some people have written on their profile that they are currently not interested in language exchange, so make sure you check people's profiles first.

It only takes a minute, 30 seconds to reply: "Thanks for your message but sorry, I already have enough language partners/don't want a language partner". But it seems people'a lives are so busy that they can't even spare this time to be polite!