How do people survive hits in Raids?

I’ve always wanted to do raids but groups seem really rare now, and decent groups that don’t quit after dying seen even rarer. I actually managed to find a decent group that was happy to run raids all day long, but I feel like I’m really letting the side down. The drill stage and the lockdown stage seem to be where I really struggle.

The drill stage is just a pain in the butt anyways, but I seem to die from single hits, but when I’m observing my teammates, I see them shrug off hits with barely a blip to their health. How do they survive the hits that one shot me?

Secondly is the lockdown stage, I feel like just jumping up high and letting my teammates who seem to know what they’re doing handle the stage is for the better, but is this seen as lazy? I’d help if I felt like there was a way where I wasn’t just getting in the way.