Ah yes, who could forget timeless classics like Dillon's Rolling Western and Eco Shooter: Planet 530.
Nintendo's lack of new first party-developed IPs has been a running complaint since the 90s. They get away with it because their tent pole series are so damn good/iconic...but the quality over quantity approach has led to long dead spans in the release schedule since the launch of the N64.
Let's take stabs at smaller new IPs (Why are we doing that again?) and ignore all the new IP's that's actually has either sold a ton of games or being critically acclaimed.
We're not talking about lacking new Ips like Blizzard or Bethesda here... there's plenty of new IP over the past 15 years.
1-2 Switch, Arms, Splatoon, Labo, Xenoblade Chronicles, Nintendo Land, Wii Sports / Wii Play / Wii music / Fit / Party, Tomodachi Life
Nintendogs/cats, Brain Age, Style Savy, Art Academy, Tokyo Mirage Sessions, Pandoras Tower, Last Story, Codename Steam
And while the characters are old these are also new IP's in the same timespan: Hyrule Warriors, Fire Emblem Warriors, Mario & Luigi RPGs, Mario & Sonic, Mario Maker, Warioware, Captain Toad
I'm sure there's more but from a quick peak those came up. That's more than a brand new IP each year over the last 15 and again these are probably not all of them. Having a stable of so many IPs as Nintendo has, we're obviously going to see returning games of the most popular franchises ona regular basis over new IPs. But there's definately new IP's across multiple platforms.
I do however agree that there has been times where the droughts have been pretty bad. Especially the Wii U era outside of the year 2014 was dead and the end of Wii/GC eras.
Switch has been pretty good so far i'd say presenting a good mix of new IPs, returning IPs and ports of games that suffered in the Wii U Era for a grand total of 26 Nintendo published games.