Sorry to hear your first Zwift experience was not the greatest. As someone who started Zwift just under a year ago I can empathize with your feeling of not really understanding how things work right off. I can take a bit of time to learn the ropes, as with anything new, but the learning curve is pretty quick and there are lots of folks on this forum to help you out, so just toss out whatever questions you might have and we’ll do our best to answer them.
Starting with routes, I’m not sure what world you got tossed into, or what route you were put on, but there are definitely a number of options from which to choose that will not put you onto steep climbs like that. As a start, you might want to try choosing ‘Watopia’ from the menu when you first log in (top center of the screen, but it won’t be the default selection, which would be New York today). From there, in the ‘routes’ section (just below) pick something like ‘Volcano Flat’ or ‘Tempus Fugit’. (Tempus Fugit is probably the flattest route in all of Zwift.)
And are you using the Zwift Companion app? If so, you can use the functionality in that to make a u-turn, as well as to choose other turns at the various intersections, should you decide you want to deviate from the initial route you chose. (If you just want to stay on the initial route there should be no user input necessary at intersections.)
I hope that will get you a better start for your second go at Zwift. If you run into other issues, or just have more questions, this is a great place to come for answers! And, truly, once you get the hang of it I think you will really love it.