The emphasis should be on "our" in the title: I think they mean Portugal's first involvement, which was around 1984. If you took "our" to mean Earth, then other PCs predate the ZX Spectrum and these.
Of course there was the 'holy trinity' of the TRS-80, PET and Apple II in 1977. But even with Sinclair, the ZX80 / ZX81 came before the Spectrum.
https://cybernews.com/editorial/the-1977-trinity-and-other-e...
Indeed, I was part of this generation, the first real computer I got, by opposition to build your own kits from electronic stores, was the Timex 2068 from that same factory.
Only recently I got to understand Timex spotlight in USA was long gone, while in the Iberian Penisula it was still all over the place, alongside ZX Spectrums and some MSX models.
I never knew anyone with a C64 back then.
Then the next computing wave was mostly Amiga, there were some people with Sam Coupe, until Windows 3.1 came to be, which is when I left my dear Timex 2068 into PC land, buying on credit, hardly anyone could afford paying on the spot.