It’s not if an accident is going to happen, it’s when. It’s best that you are prepared to avoid them with some quality protection.
Some people have been strapped into kneepads since they were toddlers and wouldn't dare make a step without them and others are just coming to terms with what the benefits of being protected are. How would you like to repetitively fall and get up time and time again? What a shame it would be to be sitting on the sidelines watching all of your friends having fun because you decided protection wasn't important enough.
It is always a good idea for beginners to have as much equipment as possible because unpredictable things happen all the time, and when you are just learning, your tumbles can be all kinds of bad. Grab a measuring tape and measure the largest part of each limb to see what size category you fall in under each manufacturer.
Protective gear is a big market in skateboarding and longboarding with lots of different products available to meet all of your needs. Hate kneepads but need protection? Got it. Smashed your elbow on a mini ramp a million times and need a pad? Got it. Rolled your ankle? Got it.