"SATA" stands for "serial ATA", and has the same basic command set as the PATA from 1984 - bridge chips were widely used. And it all uses SCSI, which is also what USB Mass Storage Devices use. Or if you're feeling fancy, there's a whole SCSI-to-NVMe translation standard as well.
HDMI is fully compatible with single-land DVI-D, you can find passive adapters for a few bucks.
There's one port you forgot to mention: ethernet! A brand-new 10Gbps NIC will happily talk with an ancient 10Mbps NIC.
It might look different, but the pc world is filled with ancient technology remnants, and you can build some absolutely cursed adapter stacks. If anything, the limiting factor is Windows driver support.
The basic peripherals (keyboard and monitor) of today still present the same interface as they did back in the IBM PC era. Everything else is due to massive hardware expansion, not hardware churn.
How often do you update your drivers compare to your typical internet connected app? Software that handles the idiosyncrasies of the hardware (aka drivers) generally has a much longer lifespan than most other software; I don't see how you can reasonably say hardware breaking backwards compatibility is why software keeps changing.
So pretty much none of the peripherals--including things like system memory and disk drives, do note--from a computer in 1995 can talk using any of the protocols a modern computer supports (save maybe a mouse and keyboard) and require compatibility adapters to connect, while also pretty much none of the software works without going through custom compatibility layers. And based on my experience trying to get a 31-year old Win16 application running on a modern computer, those compatibility layers have some issues.