Back when I was a little kid and had my first experience with Brawl, I didn't know who most of the characters were. I was a pokemon-obsessed kid who played nothing else. I didn't even own a Wii - it wasn't my own copy of Brawl that I was playing.
But you know what? I learned to appreciate a lot of those characters anyway.
There characters, despite me having no prior experience with them, are all ones I remembered for years to come. There are some characters here that I would have inevitably become a fan of without Smash Bros introducing me to them (Link, Meta Knight and DDD, Marth and Ike). Some of these characters I ended up playing their games because of Smash Bros exposure (Olimar, Diddy Kong, Fox and Wolf, Samus, Pit). And then there's characters who I don't even care for their source games but still appreciate in Smash Bros (ROB, Captain Falcon). But the point is I was still able to enjoy them all even without knowing who they were because I could find something to appreciate about their inclusion, and those characters all stuck with me.
This is why it boggles my mind when people get so angry that a character they didn't ask for makes it in. Thankfully it doesn't seem to be happening much this time around now yet, but I know it's going to happen with one reveal eventually. But you don't have to know a character to appreciate them in Smash Brothers. Even when 4 came around, I wasn't familiar with Mega Man, Bowser Jr, or Monado Boy but I still enjoyed playing as all of them because they each brought something with them. And I know I'm going to enjoy playing as the Belmonts because they seem to have a really unique playstyle.
If you don't know a character who makes it into the roster, give them a chance. They might be someone you didn't even know you were a fan of. I don't particularly want Geno, Banjo or Isaac, but if by some miracle they all made it in, I'll definitely give them all a try.