[Update] I was at a bike park with a group of absolute newbies. Here’s what I told them and how it went.

So after the overwhelming number of repsonses in the initial thread ( https://www.reddit.com/r/MTB/s/zbomnbUG5N ), I consolidated the answers and worked my own ideas into the list. The evening before we went to the park, I read the list of things to the group, showed basic bike positioning on my own bike, let everyone touch brakes, etc. and answered the questions that arose.

The next morning we went to the rental shop and picked up the bikes and protection we had booked. These were the bikes we got: Ghost Riot EN Universal

Easy to set up and figure out MZ suspension, powerful Shimano brakes with 200mm discs, wide bars, dropper post. A nice allround enduro rig I'd say.

Everyone also got a full face helmet, a jacket with chest-, back-, shoulder- and ellbow pads and some knee/shin guards.

I reminded everyone to take it easy, familiarize themselves with the bikes and especially the brakes and then we rolled into the practice area of the park. We rolled a couple of berms and worked on basic body position, bike movement and braking for maybe 20 minutes. Then we rolled into the first blue trail.

Of course everyone looked a little clumsy at first, but after a couple of laps, some iteration of what I said the evening before and the occasional reminder of rider specific things, everyone seemed to have a pretty good time. Everyone rode multiple laps, even though the weather was awful and noone got injured. A little slip here and there, but nothing major.

We kept it to green and blue trails at first, some people also joined me on red trails later during the day.

For more context since the questions were asked via direct messages a couple of times: We were a group of 10 people, ages ranging from early 20s to early 40s. We work together as an infrastructure team in a tech company. The company paid for the entire trip. We were at Bikepark Winterberg in Germany https://www.bikepark-winterberg.de/ . We specifically went there on a weekday so it wouldn't be too busy.

Thanks everyone for your input, there were quite some things in the original post that made this trip safer and more enjoyable for everyone.