I'm not sure how driving education in your country is like but we Germans have to go through 18 or so hours of practical and 14 hours theoretical lessons and then take a theory and practical test so that should prepare you as far as driving goes.

Your parents are right Motorcycles are deadly and that's not because you drive bad, sadly. The accidents that can cost you your life are usually a cars fault (My dad almost died and the car driver didn't even realise until like 10 seconds later, luckily just shattered his knee and broke a bunch of bones) I'd suggest watching this. You should keep in mind though that it is fairly safe if you keep an eye out for Cars and stay far enough away from idiots on their phones. Other than that don't drive really fast as a beginner and depending on where you live you might need to throttle your bike for the first few years anyway (Unless you are 24+ y.o. you need to throttle your bike to 34kw/48hp for two years if you live in Germany USA probably has different laws) if not I'd still suggest not getting a huge machine with tons of power, as mentioned in the video a smaller dual sports bike is cheap and can be easily fixed when you drop it (not if but when, you will drop it trust me)

So let's summarize:

-Tell your parents are correct that motorcycles are deadly but if you are old enough to drive one you are old enough to know what to look out for

-Tell them you will get a small bike -> if you mess up it's cheaper and you can't kill yourself as easy with less power

-Do some research together and ALWAYS ride with full protection (Helmet/Gloves/Boots/Pants/Jacket/Back protector if it's not integrated into the jacket)

-Start with driving a car to get some experience on the road