n̥ is just the "not" prefix. The "ero" is the real root. The prefix applies to the root first, and then the other pieces have their meanings, usually. (Its a reconstructed language. There are both exceptions and things we don't know.)

"n̥-s-ero-" is sort of < "not" next-is-plural "mine" >.

So, plural-(invert mine). Or roughly close to "we".

"n̥-h-ero-" is sort of < "not" next-is-inclusive-plural "mine" >.

So, plural-(group (invert mine)). Or roughly close to "us".

But both are pretty close to the same meaning. High German maintained a lot of PIE, and is very close in a lot of ways. Though... Welsh is closer.

I've never heard of it being based on that root before. Do you have a source?