The thing that made Jobs consequential was the old Henry Ford-ism of "If I'd asked people what they wanted, they'd have asked for a faster horse."
Dennis Ritchie did a damn fine job making what he did, but what he did was essentially just going with the flow; unix and C are like selling sugar to bees. They essentially "sell themselves"; they have qualities that programmers look at and inherently go "I want that!".
What Jobs did was going against the flow.
I'm going to go ahead and say something outrageous: we wouldn't have gui software without him. Or more accurately; it would be about as common as Lisp or Smalltalk. You'd have these isolated islands of gui development for a few specialist apps, but it would basically be workstation stuff, because only dedicated, specialist machines would be capable of running it.
What he understood was that most changes in technology aren't caused by historical inevitabilities or meritocratic ascendence of technology that's ready for prime-time, but are caused by social factors. GUIs had been technologically ready for years, but would only take off with the right social factors. One of these was to have a platform where all machines were guaranteed to have all the necessary ingredients to support GUIs; it was "safe" as a developer to do that, because you knew the entire addressable market could run your stuff. Furthermore, they took the "crazy" additional step of expressly forbidding non-gui ports from other platforms for a few years, and kept it quite difficult to do after that embargo ended. They adamantly wanted people to come up with brand-new, gui-based solutions to common app categories, rather than just porting over some famous app from a command-line paradigm.
This was critical - both MS Word, and Excel were born in that environment (yes, as mac programs, first), and it was particularly because Excel didn't get stabbed in the cradle by now-forgotten juggernauts like VisiCalc. If VisiCalc had been ported to the original mac, Excel wouldn't have stood a chance.
But that's emblematic of what it actually would have been like: if VisiCalc even could have been ported, that's what 90% of mac software would have been - command-line apps. Even native, non-ported apps are would have been mostly command-line apps, because they're just plain easier to write. At that point, it's not a Mac - it's not even a GUI machine then, and why would you even buy it if it didn't do anything unique? They had to artificially prevent that to "jump-start" us into a world where everything would actually all be gui stuff, across-the-board, no matter what, to allow us to experience what that's actually like.
----
That was the trick; it was a "gateway drug". Once you'd bought a machine to run Excel or Word, suddenly you had the ground conditions that made it possible for something like Photoshop or PageMaker to exist. You couldn't make a business out of apps like these without a large market of people already "forced" to be 100% gui-and-mouse. Spreadsheets are possible on a commandline, if awkward. Drawing apps (not plotting apps, drawing apps) are impossible without a mouse. And without that captive market, the business case to dare making them couldn't be made, nor could the "hey, that's only $100, let's buy that on a lark because I've already got a machine that can run it" rationale be possible.
This wasn't an accident. This was planned.
Much like a competent city planner; this wasn't a historical accident, but was a deliberate consequence of choices intended to achieve it. Jobs saw exactly what socio-political-economic forces were preventing this from happening, and set up an "artificial greenhouse" where these proverbial plants could take root, and grow big enough to survive outside the greenhouse.
----
Another great example of social forces like this was phone app stores.
We've had the tech to do (considerably simpler, but functionally similar) ones as early as 1995. Early Nokia phones easily could have done gameboy-level (or palmpilot-tier) apps on a mobile store, but somehow, nothing like that happened. For decades.
It simply was not a technological problem - it was a social and political problem. The phone vendors expressly forbade any app distribution, period. Apps were pre-bundled (and hard-locked) on phones as selling perks to move the hardware, not as a fungible quantity of their own.
Only a political deal, an "offer they couldn't refuse", was capable of breaking that logjam. Apple had to play the phone companies against each other, using a new piece of hardware that wouldn't remain novel for more than a few years, and using that as a bargaining chip to demand control-transfer over the software part of the phone. Famously, several of the most successful carriers like Verizon told them to (and I quote) "go f** themselves". Only a back-bench carrier, Cingular (later bought by AT&T) was willing to humor them, but once that Pandora's box was opened, the reluctance of all the other phone vendors quickly caved. After that, because they wanted to ensure Apple wouldn't achieve hegemony over the OS supply, they quickly became favorable towards allowing other phone OSes "with app distributions" to exist.
But it's exactly that - goading the phone companies into a position where they were "politically inclined to allow app markets to exist" that was Job's genius.
We wouldn't have "not had Android because there wouldn't have been an iPhone to copy". We would have not had Android because the phone carriers would never have allowed it to exist. Nobody would be allowed to sell it - we'd all be stuck on embedded symbian-or-whatever stuff with apps pre-flashed into the firmware.
----
Politics is the greatest barrier to tech innovation. Not "actually creating the tech".
Jobs was "the politician we needed".
There's an EXTREMELY similar schtick with Elon Musk and SpaceX. Politics are the number one reason NASA and Boeing et al couldn't develop reusable rockets. It's particularly ironic in that case, because those companies had, in many cases, literally the very people who later made the breakthroughs, but those people simply were not allowed to spend their time working on it, at those companies. For almost half a century, in that case. That's how technological stagnation happens.