Ratings, class and percentile, real indicators of ability?

I consider myself a decent player and my current rating is 1418, however I have doubts about my real abilities. I never had a rating until I started playing here at Chess.com and some have said other sites may rate me differently. Also, my rating varies quite a bit, I'm on a high point right now, but with some losses could quickly drop down 100 points. It seems a matter of chance that I can happen to have a winning or losing streak. So, is the rating system a good indicator of ability if your rating can change so quickly? Perhaps computer analyses of many games and moves could calculate a better standard based on a player's tactical abilities. My faults as a player are that I have difficulty memorizing openings, so I just play daily games where I have time to make up my own moves that look good to me, even trying out different ideas in the openings, although my strategies do not always pan out as planned. I often overlook things and make many mistakes or even blunders during the games, being given here an average 77 accuracy. I just read about the class categories in chess, I suppose I'd be in like "D" most of the time, but currently, being above 1400 I'd be in "C".  But what strikes me is looking at the percentile, so am I really better than 96.9% of the players here? Maybe the typical Chess.com player is a beginner struggling to improve or a casual player not trying very hard? I understand the average tournament player is rated 1500, I can't get a swelled head when I'm way below that rating.  In the outside world is the average player more or less skilled than a typical Chess.com player? If I played a tournament, I imagine they would give me some sort of rating. Would it be higher or lower than my Chess.com one? Here I often see posts by players rated 1500 to 1700.  Are they like in the 98 or 99 percentiles? Just thinking if I should consider myself among the good players or not.

I think we have overcomplicated things with ratings and classes of chess players, the old classification system is much simpler to grasp, basically there are 4 categories of chess players 1.Beginners and novices 2.Amateurs 3.Experts 4.Masters I would say u and I both belong to category of amateurs , if you want to assign ratings to these different classes then beginners would be like below 1200, amateurs be like 1200_2000 , experts 2000_2400 and masters over 2400, so u can call yourself a decent amateur chess player

Sadlone - Thanks for the response to my question. I'm certainly no expert, but still feel puzzled that such a large percentile of players here rate lower than me. Looked at your games and see you like computer opponents and are rated a bit over 2000, much higher than me and, by your criteria, an expert player!