This game is extremely hostile to new players

My friend has been trying to get me into Dota 2 and so far it has been a miserable experience. I am not new to MOBAs so I know how all of it works, just new to Dota 2 (actually used to play the original Dota on Warcraft 3) and remember some of the heroes. I played a few games with bots, found a hero I liked (Sniper), just wanted to keep playing sniper for a while first.

The first game against humans we got into went on for 80 minutes, even though we were clearly going to lose the other side just would not push and win. And apparently there is no surrender option (if true that is insane)?? Anyway I didn't think it was going to take so long and had to go to an event so I could not sit at the computer any longer so I left. The next time I tried to play I found out I am in a penalty queue for that, and have to win 2 games to get out of the penalty queue. Except in that queue I am only given a choice between 3 random heroes, none of whom I know how to play so I am a new player plus always playing a new hero. Needless to say it is next to impossible to win like this, I have tried about 8 games so far (all miserable with people yelling at me sometimes in other languages), lost every time. Still in the penalty queue. I am pretty much at the end of my rope, I am just going to go back to League of Legends.