Before the PC dominated there were lots of idiosyncratic machines with idiosyncratic architectures. Most of them were useless to the average consumer. Computers were used by businesses and scientists; and unless they had a small business, the average person was unlikely to want or need one.
The uses that did take off involved children: education and gaming. Many "home computers" were basically video game consoles in terms of hardware, but they had keyboards and could be programmed. People sold commercial games for these systems, but they were also the first systems for which kids got interested in making their own games. You had to have an interest in programming the machine to a very low level in order to make a game; there was no Unreal or Unity to hold your hand. But the machines were simple and well documented; every bit of hardware (graphics chip, sound chip, joystick port, etc.) had info on how to program it in the manuals that came with the machine (at least for common machines like Commodore ones).
Some of them, most notably the Apple II (US) and BBC Micro (UK), were purchased by schools for educational purposes. Special "edutainment" programs would be run on them to teach kids things like math, reading, and geography. The most famous such program was The Oregon Trail, which simulated an expedition across the western United States before it was settled, but there were hundreds of such programs across the many different computing platforms.
In the 8-bit PC era, because it was unclear what people would use PCs for, it was also expected that they would come up with their own applications and to that end almost all of them came with the programming language BASIC, allowing the user to get started with programming right away. This was considered something of a high point in computing history, because it gave the notion that computers were there to be programmed and to do exactly what their users wanted. As 16-bit and 32-bit machines took their place, programming tools became optional add-ons and it took more and more time and cost to write useful programs for them. Some of the non-IBM-compatible 16-bit machines, like the Atari ST and Amiga, retained some of the "game console" architecture and had amazing graphics and sound capability. With the right tools you could do some really impressive things with them.
PCs didn't become common consumer products until the mid-late 90s when the biggest consumer killer app emerged for them: the internet. This corresponded nicely with the release of Windows 95, the first end-user Windows OS that could run full-fat 32-bit applications. Now that they had a primary purpose for the average consumer, interest in marketing them as programmable devices waned over the next three decades to the present day, when the idea is to prevent the end user from running any but preapproved software, especially on the PC's replacement as internet gateway: smartphones.
We had much more fun with our janky little machines back then, even if we couldn't do nearly as much. We've reclaimed a little of that with open source operating systems like Linux and BSD, but it's still not quite the same.