The Neptunian desert and savanna have been recently found to be separated by a ridge, an overdensity of planets in the ~3-5 days period range. These features are thought to be shaped by dynamical and atmospheric processes. However, their relative roles are not yet well understood. We intend to confirm and characterise the super-Neptune TESS candidate TOI-5005.01, which orbits a moderately bright (V=11.8) solar-type star (G2 V) with an orbital period of 6.3 days. With such properties, TOI-5005.01 is located in the Neptunian savanna near the ridge. We used Bayesian inference to analyze 38 HARPS radial velocity measurements, three sectors of TESS photometry, and two PEST and TRAPPIST-South transits. We tested a set of models involving eccentric and circular orbits, long-term drifts, and Gaussian processes to account for correlated stellar and instrumental noise. We computed the Bayesian evidences to find the model that best represents our data set and infer the orbital and physical properties of the system. We confirm TOI-5005~b to be a transiting super-Neptune with a radius of Rp_=6.25+/-0.24R_{Earth} (R_p_=0.558+/-0.021R_Jup_) and a mass of M_p_=32.7+/-5.9M_{Earth} (M_p=0.103+/-0.018M_Jup_), which corresponds to a mean density of rho_p_=0.74+/-0.16g/cm^3^. Our internal structure modelling indicates that the core mass fraction (CMF=0.74^+0.05^-0.45) and envelope metal mass fraction (Z_env_=0.08^+0.41^-0.06) of TOI-5005 b are degenerate, but the overall metal mass fraction is well constrained to a value slightly lower than that of Neptune and Uranus (Z_planet_=0.76^+0.04^-0.11). The Z_planet_/Z_star_ ratio is consistent with the well-known mass-metallicity relation, which suggests that TOI-5005~b was formed via core accretion. We also estimated the present-day atmospheric mass-loss rate of TOI-5005 b but found contrasting predictions depending on the choice of photoevaporation model (0.013+/-0.008M_{Earth}/Gyr versus 0.17+/-0.12M{Earth}/Gyr). At a population level, we find statistical evidence (p-value =0.0092^+0.0184^-0.0066_) that planets in the savanna such as TOI-5005 b tend to show lower densities than planets in the ridge, with a dividing line around 1g/cm^-3^, which supports the hypothesis of different evolutionary pathways populating both regimes. TOI-5005 b is located in a key region of the period-radius space to study the transition between the Neptunian ridge and the savanna. It orbits the brightest star of all such planets known today, which makes it a target of interest for atmospheric and orbital architecture observations that will bring a clearer picture of its overall evolution.