  CrBr$_3$ is an excellent realization of the two-dimensional honeycomb
ferromagnet, which offers a bosonic equivalent of graphene with Dirac magnons
and topological character. We perform inelastic neutron scattering (INS)
measurements using state-of-the-art instrumentation to update 50-year-old data,
thereby enabling a definitive comparison both with recent experimental claims
of a significant gap at the Dirac point and with theoretical predictions for
thermal magnon renormalization. We demonstrate that CrBr$_3$ has next-neighbor
$J_2$ and $J_3$ interactions approximately 5\% of $J_1$, an ideal Dirac magnon
dispersion at the K point, and the associated signature of isospin winding. The
magnon lifetime and the thermal band renormalization show the universal $T^2$
evolution expected from an interacting spin-wave treatment, but the measured
dispersion lacks the predicted van Hove features, highlighting the need for a
deeper theoretical analysis.
