I feel like it's a stepping stone in more ways than one. There's still plenty we don't know about how our own biology functions outside of Earth's gravity well

I feel like it's a stepping stone in more ways than one. There's still plenty we don't know about how our own biology functions outside of Earth's gravity well, atmosphere, or magnetosphere. Long term studies will need to be done, and lunar studies are a much more approachable candidate (cost and mission risk). We could always go straight to Mars and do the research there, but that is the riskier strategy. We'd definitely learn what we need to, but it opens up more failure modes for any colonization mission, and managing the risk on Mars would be expensive. Mars colonization would already be straining our ability to engineer and fund, let alone doing it semi-blind.