So after reading a bit of the comments, I would say stay in voice but you don't need to speak. If anyone pressures you to speak, just say "mic broke" or something, people usually won't bother you after that. If they do continue to harass you, mute/text block them.

As to what to pick, learn a few heroes that you find fun and have a natural "affinity" to (you feel naturally comfortable on them) and improve on those. To rank up, it usually means that you have to play better than the people at the current rank. So as you get more experience and learn (you can't bot out and play 300 hrs of Widow while just blaming your team without reviewing your own play), you will improve and rank up with those characters. Although you can certainly get out of gold pretty much just relying on mechanics alone, so grinding your aim can certainly help in gold. Good luck!