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That's a lovely carbine, and they are rare. You're lucky to have the original cleaning rod, and what appears to be the original sling. I can't get exact figures for the production of these carbines, but they appear to be far scarcer than the long rifles with similar markings. [EDIT: Ron Bester considers there were about 2000 ordered, serial numbers 3000 - 5000] Almost all are dated 1897. Regarding the stamps on your carbine's buttstock, I don't think they're of Boer origin and not South African military or UK military acceptance marks, which would also be on the metal. They're likely to be an inventory mark e.g. from some cadet force.
For comparison, I attach photos of mine, serial number 3004. Though not bought by the OVS, mine was apparently used by an OVS burgher.

On a closer look, the pit on your loading ramp is something I wouldn't expect - suggest check it carefully. SA cadet forces did a variety of things to their parade arms to render them unable or unsafe to fire.
The S on the side of your receiver is an added marking.

Yoiur carbine is absolutely lovely. Wonderful carved stock!

Your information about cadet units may very well apply here. The extractor is missing and the striker doesn't engage, so it is indeed completely disabled. I would love to get it functioning again but not very hopeful of that. I didn't get it to shoot, but would like to at least make it functional if anyone has suggestions.
Still, the cadet information adds to its history as it certainly appears to be the case.

I was wondering about the S mark as well. Perhaps a South African equivalent to "Sold Out of Service?"