From your post, you aren’t really all that far off! Naturally you’ll find a character who just clicks with you (if you haven’t already) and things will just begin taking off!
If you get discouraged watching certain tips and tricks is always helpful. Lord knows I would have suffered trying to do Mercy’s super jump otherwise.
At this point, don’t even acknowledge the number. Your ability is far more than just a number that the elusive MMR and a handful of matches has chosen for you. You’re new! Give yourself credit where it’s due.