Curiously, Old English unc is actually not related to German uns, at least, not after the Germanic language family had already formed. Old English at some point underwent a sound change[1] where the -n- sound disappeared before fricatives (sounds like s, f, v, z, sh, etc...). So "us" comes from an older common form "uns", which German inherited basically unchanged. This sound change also explains other correspondences between English and German where the n is missing, like mouth-Mund, tooth-Zahn, other-ander, goose-Gans or five-fünf.

1: https://en.wikipedia.org/wiki/Ingvaeonic_nasal_spirant_law

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.

As a born German, now more native English speaker (left at 8), I agree. But, unless I'm very wrong, uns/unser in modern German is not restricted to 2 people either - it can mean 2 or more, as in "unsere Gemeinde" (our church, referring to something shared by hundreds of people)?

That was my first thought too! So many things in old-english are very very close to modern German, so it's sometimes surprising to see these false-friends.

Same with Ic - Ich