Horse actually do invent and create. It’s just since they are in the narrative B team, you usually see their inventions more prominently basically anywhere else.
Elemental phenotype
Tankwarriors
Chem lasers
HAG
Quadvees
Elemental III
Clan interface cockpit.
And the Hellbringer as HobbesHurlbut mentioned.
And the Nova as Natasha Kerensky mentioned.
In addition, the Nova was the first Omni to feature mechanized Elemental hardpoints, add that to the Horses's list. The Horses didn't invent OmniTech, but they were the first to apply it to vehicles. In Era Digest Golden Century the Horses were credited with the creation of Clan-spec Narc (it also mentions TAG, but I don't remember any difference between Clan and IS TAG).
Maybe Peter Cobb will evolve in time to be an actual character, as opposed to being a plot advice to voice all of the problems the Horses have going on. Most of the ideas he presented in the book weren't really all that innovative for the Horses (but were still somehow treated as revolutionary and "dezgra"), and I never once got a sense that he (or anyone in the book, really) had an actual vision for what they wanted the Horses to be/do. But right now, I could swap out Peter with (to use more current examples) Noritomo Helmer or Knives Out Chistu and I honestly wouldn't be able to tell the difference. Just the same ol' "our leadership sucks, we need to find ourselves again" cookie-cutter Clan archetype. It astounds me that with such an alien culture, rife with potential, the same played-out tropes continue to bob to the surface.
I don't see these as play-out tropes. Characters like Cobb, Helmer, and Chistu are the consequence characters that show up when the "alien culture, rife with potential" characters try something new, but don't succeed. The "return to the old ways" types are seem so boringly obvious, but you only see them when something new fails. Whenever we see a character do something new and succeed, there's no need for the "return to the old ways" types. The few exceptions are the Prinz Eugen mutineers, those who stayed behind in the Pentagon worlds during the 2nd Exodus, and in a way the Word of Blake. Each of those type of old-ways types fought to return to the old ways, but were put down.
Take a look at some of the new ways characters that succeeded. Vlad Ward negated a Trial of Absorption against his Clan, essentially formed a new Clan, and together with Marthe Pryde created the harvest trials where units from one Clan initiate a trial of absorption trying to get captured into another Clan. I can't remember the name of the Khan, but whichever Sea Fox Khan made the switch from Clan with enclaves, clusters, and galaxies into the roving band of armed merchants, Khanates, and aimags. Similarly is the Ghost Bear Khans who instead of merely claiming IS worlds ended up merging with the IS worlds to the point the Clan became only a part of the whole Rasalhague Dominion and not the rulers over their people.
Cobb has surfaced because Amirault and Lassenera failed the Clan through their plotting instead of acting and obsession over hurt feelings. In many ways they both made things worse in their stubbornness. At least Malvina's supporters can point to a long string of battlefield victories & territorial expansion. It didn't work in the end goal for the Falcons, but it got them far closer than the Horses.