If you want to get into Resident Evil and want to start from the beginning, the HD remaster of the Gamecube remake of Resident Evil 1 is on Steam.

It is often considered one of the greatest remakes of all time and widely thought to surpass the original while preserving everything that made the original great (with the exception of the cheesy FMV cutscenes and dialogue. The remade dialogue is still cheesy but not nearly as funny) unlike the 2/3 remakes that change the games completely.

Technically Resident Evil 0, the HD remaster of which is also on Steam, is the actual beginning of the story in terms of the series' timeline but I would not recommend it to a newcomer. Consider it advanced studies to come back to later.

The only main games which do not have modern PC ports on current storefronts are 2, 3 and Code Veronica and there are multiple ways to experience each on PC.

I grew up with the PS1 so I tend to just emulate those versions for 2 and 3, which is honestly rather painless with Duckstation, but there are plenty of other ways. You could also emulate the Dreamcast or Gamecube ports of said games, and I believe the GC version has a mod for HD backgrounds.There's also the Classic Rebirth Patches for the Japanese-only PC ports which can be found floating about online.

As for CV, you have the original Dreamcast version and the Code Veronica X port for PS2 and the later HD ports of CVX for Xbox 360 and PS3. All four can be emulated, though IIRC there's issues with emulating the 360 version. Also some people are not fans of the changed lighting in the HD remake in general. I just emulate the PS2 version with PCSX2