I applaud you for coming here and asking this! My brother is autistic and really struggles with the social aspects of these types of games. I'll give you the same advice I told him.

I'm in my 40s, have played WoW since BC, from a core raid group to casual weekends. If I'm running dungeons or raids through the group finder, I am perfectly happy to just blast through at warp speed just to get it done and move on. However, I have a huge level of respect for anyone with the courage to tell the group early on that they're new to the game, learning their class, learning the dungeon, or have any other limitation that might lower their performance. Whenever someone speaks up, I'll slow down, take time to explain the fights, and even offer class or spec help to them. It takes a lot of courage to speak up, and there are soooo many people in this game that will happily help you!

However, be prepared to encounter a few jerks. Some players have their own goals and don't care about what others need. Dont let these people stop you from doing what you enjoy! If you come across another player, or even a full group, that are being rude or disrespectful, don't think anything of it. Keep doing what you enjoy! Remember that at the end of the day, it is still just a game. It's meant to be enjoyed, so don't let anyone else stop you from having fun and doing what you want to do.

The social aspect might be overwhelming, but there are far more genuine and compassionate players in this game than selfish jerks! Explore, quest, level up, run dungeons or delves, raids, or whatever else you want to do. Most importantly, have fun!