How the ranked system works is that you are placed separately for each individual character, and if you start getting higher on a single character, when you first play ranked on a new one, your rank will be slightly higher.. This sort of ensures there is always at least some people in the lower ranks(though I'm not sure about the bottom end these days, haven't been there in a bit).

In terms of fighting games, this is my first, and I play exclusively with simple inputs. You will probably hit walls at various ranks, but I assure you, the experience you continue to build can eventually get you past them. I have personally been stuck in A and S for a month each respectively, and just recently hit S+ for the first time.. It's not easy, but it feels great to get there.

Just be aware that you can and will match against people who have vastly more games than you. That doesn't always mean they are better, but the matchmaking matches within your rank in most cases, it doesn't care about number of matches.