Letting the monsters loose is a happy coincidence. More importantly, it doesn't have a lasting effect on the character. Not like, say, getting one's hand chopped off by Vader or having one's home burned down by Stormtroopers. Her escape from Kylo Ten is also a cakewalk due to the OP force powers.
And yes, the fact she doesn't fail enough is my whole point. Her arc is a pretty basic action hero arc, but it fails at making the hero suffer to any significant degree, thus making their eventual triumph vastly less satisfying. Being captured by Ren is her only major slip-up, but it doesn't leave any lasting effect on the character. It's basic storytelling, and they screwed it up.
There's a lot of this going on: well she doesn't fail ENOUGH, and then an immediate comparison to Luke.
The fact that the tentacle monsters helped as much as they hurt (Finn almost died to them) doesn't really change the fact that she fucked up. To use an analogy, if I drove drunk, the fact that I didn't hit anyone wouldn't be a defense against the fact that I made the wrong decision and endangered others.
As for losing the hand and uncle... Well, I don't think it's really fair that we're looking at Luke's whole character arc across the films to compare to Rey's sole outing. Luke didn't lose his hand until. The end of the second movie, and he immediately got it replaced with a mechanical one that functioned identically and didn't even look wierd. And please remind me how Luke's aunt and uncle being murdered was his fault?
I went over the conflicts that Rey faces both internally and externally. But the truth is that Rey is in a shitting position than Luke at the beginning. Luke had people who cared for him. Rey had a scumbag boss. She lost less than Luke because she had nothing to lose until Finn and Han entered her life to give her an out from that hellhole.