The transport of low-energy ion beams in plasmas is a fundamental problem in magnetic confinement fusion, proton-beam fast ignition, and high-energy-density physics, because the charge state directly controls the interaction strength between ions and plasma particles and therefore affects stopping power, penetration depth, and energy deposition. In the Bohr-velocity regime, ionization, electron capture, and recombination processes strongly compete with one another, so the average charge state becomes highly sensitive to the microscopic properties of the target plasma. While most existing models assume that background electrons remain close to thermal equilibrium, this assumption may break down for intense ion beams, where collective beam-plasma effects can substantially modify the electron velocity distribution.In this work, we investigate the influence of return-current electrons generated by the two-stream instability on the average charge state of low-energy proton beams propagating through partially ionized hydrogen plasmas. A kinetic model is developed by coupling a parameterized beam distribution, a thermal-electron component, and a drifting return-current-electron component into the relative-speed-distribution formalism. The resulting relative collision-rate distributions are then introduced into a multi-channel charge-exchange rate equation system that includes ionization, excitation, de-excitation, electron capture, radiative recombination, and spontaneous decay among the hydrogen states with principal quantum numbers n \leqslant 3. This framework makes it possible to evaluate how collective effects modify microscopic atomic rates and, in turn, alter the equilibrium charge-state population of the beam.The calculations show that, when two-stream instability becomes important, the ion-electron relative speed distribution is strongly reconstructed by the emergence of return-current electrons. Compared with the conventional thermal-electron model, the return-current component shifts a significant fraction of ion-electron collisions toward lower relative energies. As a result, part of the electron-impact ionization channel is suppressed because the corresponding collision energies fall below or closer to the ionization threshold. In contrast, the electron-capture rate increases only slightly, and this increase mainly comes from the broadening of the beam-ion velocity distribution rather than from the return-current-electron drift itself. This imbalance reduces the average charge state of the transmitted proton beam.For typical plasma conditions with an ionization degree of 50\text%, an electron temperature of T_\mathrme = 10 eV, and an electron density of n_\mathrme = 1\times10^13\;\mathrmcm^-3, the inclusion of two-stream-instability-induced return-current electrons lowers the average charge state by about 11.9\text% at 30 keV and by about 2.2\text% at 100 keV. The effect weakens with increasing beam energy because ionization progressively dominates over capture in the higher-energy range. Calculations with varying beam density further show a two-stage reduction behavior: the charge-state decrease first grows rapidly with increasing n_\mathrmb/n_\mathrme and then becomes slower after the return-current-electron contribution approaches saturation. In comparison, the broadening of the beam-ion velocity distribution alone produces a much smaller correction to the total charge-exchange balance.These results indicate that, for intense low-energy ion beams in plasmas, collective effects cannot be treated as a correction to transport only at the macroscopic level. Instead, they also reshape the microscopic collision-rate distribution and thereby modify the charge-state evolution itself. Since the stopping power scales approximately with the square of the projectile charge state, even a modest reduction in average charge state can lead to a noticeable change in energy deposition. The present study therefore provides a physically transparent framework for incorporating non-equilibrium electron distributions into charge-state calculations and offers useful guidance for ion-beam transport modeling in fusion and high-energy-density plasma environments.