I think everything is fine with that bike. I think the op isn‘t used to vintage bikes.
- it has cottered crank. Nothing wrong with that. On the contrary. If it gets loose due to improper installation, reinstall correctly with a new cotter pin and off you go. Riding a loose square taper crank destroys the whole crank.
- It doesn‘t have disk brakes. No problem either. Learn to squeeze those levers hard with multiple fingers and you‘ll stop in time.
- Guess it‘s a 5 speed freewheel. The difference between gears can be 3 or 4 teeth. Guess that‘s meant with slop/slamming. Just get used to it. Or use a half step chainring setup and learn the double shift patterns. And don‘t shift under load.