Are people going to think 'fat cow' when I stop after 5 minutes to take a break? Is it going to be loud because I'm heavy?! Not even sure what speed to set it at to start.
If I'm on a treadmill, I am in my own little world of gasping for breath, counting my strides, watching the clock. Honestly, if I'm working hard, I don't have the brainspace to do anything other than survive the next interval of 30 secs at a scary pace, or a minute with an impossible gradient.
I am not thinking "OOoooh that person 3 machines along is making a racket" If I did notice the noise, I'd think "Gosh, they're working hard."
When I started running - on a treadmill like you - I used a Couch to 5k app. And I set my pace at around 7 k per hour, with a walking pace of 5 kph. All at a gradient of 2.0 - apparently this is the nearest equivalent to running outside.
I learnt how to jump off & on the treadmill while it was running, so if I'm now doing a workout where I have to run for 30 secs at 14 kph, and I feel I'm going to fall over at 25 secs, I can jump my feet to each side of the moving band, and gasp to recover for 5 secs.
Also re noise - all the heavy but fit men at my gym (there are some boxers and some rugger players and some amazing powerlifters) make a noise when they're on a treadmill. It's normal.