Welcome to the Zorin forum, Alex.
The background of Zorin OS is discussed in " Zorin OS: From the Hobby Project of Two Teenagers to a Growing Startup", a 2017 It's FOSS interview with Artyom Zorin, one of the two principals of the company.
raison d'etre (given the plethora of linux OS's)
The raison d'etre is to provide "A familiar desktop you already know how to use" for Linux adopters coming to Linux from other operating systems, primarily Windows and MacOS. The distinguishing characteristic of Zorin OS is the "Zorin Appearance" app that allows a user to change the desktop layout to feel like Windows, macOS, or Linux.
From the "About" section of the Zoring OS website:
Despite the enormous advantages it has over traditional operating systems, we recognized that the biggest barrier to the success of Linux on desktop computers was that it wasn't user-friendly enough. Linux-based operating systems were generally built for engineers by engineers, with little consideration for regular users. We decided to fix this.
We've designed Zorin OS to have the perfect blend of power and usability for everyone. Zorin OS was built to be as easy as possible, so you won't need to learn a thing to get started thanks to its familiar user interface. It comes loaded with all the apps and tools you need out of the box for browsing the web, working, playing and everything in between.
people/key players involved
Artyom Zorin and Kyrill Zorin
Zorin Technology Group Ltd.
backing, funding and income (besides users' donations)
Zorin's income stream is the sale of Zorin OS Pro and user donations. According to the "About" section of the website, Zorin is "funded entirely by the community". Zorin Grid is currently under development, and may become a part of the income stream when released.
long-term financial/technical strategies and goals
I don't have information about this question.
(1) Individual Linux adopters (all editions), (2) business/corporate Linux adopters seeking a familiar desktop environment to reduce training/retraining costs (Pro editions), and (3) schools and educational institutions (Education editions). The business/corporate and education market will be served by Zorin Grid, a tool that that allows organizations to set up, manage, and secure a fleet of Zorin OS-powered computers.
system (linux) basis/technicalities?
Zorin OS is a Linux distribution based on Ubuntu LTS. Zorin OS Core, Zorin OS Pro and Zorin OS Education leverage the Gnome desktop. Zorin OS Lite and Zorin Education Lite leverage the XFCE desktop.