I was expecting mostly third-parties, but that's because there are a lot more choices for them. It doesn't mean the big remaining first-parties aren't still popular.
But they aren't still popular. We live in a world where first parties are essentially
Tabuu taboo. Even an ARMS rep, who is guaranteed to be inventive and fun to play with their extendable ARMS, is viewed as "boring". The fact that after a year of 3rd parties and Byleth, the best a Nintendo character was able to get is 9th, says a lot about how unpopular 1st parties are now.
I'm surprised Dee and Shantae both ranked much lower this year than last year. Dee was in 2nd place now he is in 9th and Shantae was in 5th place now she is in 13th.
That was mainly due to the rise of 3rd parties in Bandana Dee's case (keep in mind FP1 at the 2019 point was JUST Joker, so we didn't know that FP1 was gonna be almost all 3rd parties). (Somewhat off topic, but Shantae fell victim to the rise of other indie competitors such as The Knight and Reimu who most of the former Shantae fans probably went to. Shantae just isn't as popular compared to other indie characters. This and her loss against Shovel Knight on DBX are proof of that.). Neither characters stand a chance to get in on fan demand with poor results like that. You need to be top 5 (or maybe even #1) like K. Rool, Ridley and Banjo were to even stand a ghost of a chance.