  The first JWST spectroscopy of the luminous galaxy GN-z11 simultaneously both
established its redshift at $z=10.6$ and revealed a rest-ultraviolet spectrum
dominated by signatures of highly-ionized nitrogen, which has so far defied
clear interpretation. Here we present a reappraisal of this spectrum in the
context of both detailed nebular modeling and nearby metal-poor reference
galaxies. The N IV] emission enables the first nebular density measurement in a
star-forming galaxy at $z>10$, and reveals evidence for extremely high
densities $n_e\gtrsim 10^5$ $\mathrm{cm^{-3}}$. We definitively establish with
a suite of photoionization models that regardless of ionization mechanism and
accounting for depletion and this density enhancement, an ISM substantially
enriched in nitrogen ($[\mathrm{N/O}]=+0.52$) is required to reproduce the
observed lines. A search of local UV databases confirms that nearby metal-poor
galaxies power N IV] emission, but that this emission is uniformly associated
with lower densities than implied in GN-z11. We compare to a unique nearby
galaxy, Mrk~996, where a high concentration of Wolf-Rayet stars and their
CNO-processed wind ejecta produce a UV spectrum remarkably similar to that of
both GN-z11 and the Lyc-leaking super star cluster in the Sunburst Arc.
Collating this evidence in the context of Galactic stellar abundances, we
suggest that the peculiar nitrogenic features prominent in GN-z11 may be a
unique signature of intense and densely clustered star formation in the
evolutionary chain of the present-day globular clusters, consistent with
in-situ early enrichment with nuclear-processed stellar ejecta on a massive
scale. Combined with insight from local galaxies, these and future JWST data
open a powerful new window onto the physical conditions of star formation and
chemical enrichment at the highest redshifts.
