I agree that there's often too much elitism directed at Walmart bikes etc, but it is true that they are usually very poorly assembled, even when the actual parts on the bike are, if not great, often (though definitely not always) serviceable. Bodewinham, if you need to rely on this bike as functional transportation, I really would recommend you get it checked for correct assembly by a professional mechanic or with the help of someone at a bicycle cooperative if you can. Many bike mechanics can empathize with the need to keep costs in check--just clearly state that you need to be able to rely on the bike, but want to keep costs low (as is appropriate to the bike) and don't necessarily have high expectations for its performance or long term service life.
With basically no specific information, my guess is that the chain dropped off the chainring, which is the gears in the front. The front derailleur is the mechanism that pushes the chain to shift in the front, and it's probably poorly adjusted which makes dropping the chain happen more easily.
If you are interested in doing work on the bike yourself, you could probably get your bike a large proportion of the way to being correctly assembled with the proper application of skill, 4 and 5 mm hex wrenches, and a screwdriver adjusting the shifting and brakes.
https://www.parktool.com/blog/repair...-brake-service
https://www.parktool.com/blog/repair...eur-adjustment
https://www.parktool.com/blog/repair...eur-adjustment