Jigoro Kano did not "invent" the concept of Kuzushi.
The concept of Kuzushi existed long before Judo split off from Jiu Jitsu.
What Jigoro Kano did do is create a Martial Art that focused on certain parts of Jiu Jitsu and enhanced them. The result is having a lot fewer techniques than Jiu Jitsu, but all of them being applicable by anyone of any stature.
Jiu Jitsu focuses on takedowns and the ground fight is the core.
Judo focuses more getting your opponent cleanly on the ground without using your own strength. Jiu Jitsu has these as well, but that's not where the focus of Jiu Jitsu lies.
So in short, Jigoro Kano did not invent Kuzushi as a concept, he mainly named it and focused on it.
To avoid hearsay, here are some links to martial arts that predate Judo by an entire time period that incorporate Kuzushi.
It's an Ippon Seoinage.
This is very similar to Jujutsu, but predates it.
Nihon Koryu Jujutsu, or Japanese Old Jujutsu.
Japanese old style Jujutsu, or Nihon koryu jujutsu, dates back to the Muromachi period in Japan between 1333 and 1573. This old style of martial arts training was focused on teaching the unarmed or very lightly armed warrior to fight a heavily armed warrior.
Fighting a heavily armed warrior, including heavy armour, requires not strength, but Kuzushi. This was applied in Nihon Koryu Jujutsu in the Muromachi time period.
Judo on the other hand was founded in 1882. As such, the concept of Kuzushi, which by definition is also used in Kumiuchi, Kogusoku and Nihon Koryu Jujutsu, was not "invented" by Jogoro Kano. It was however given a name by Jigoro Kano.