That's actually a really good question. It's certainly one of the key debated questions at the heart of what WotC is doing here (and as others point out, somewhat lagging the rest of the TTRPG industry, many of which got bored of "races" in the D&D mechanical sense a long time, in one way or another).

Are they archetypes for builds? Why are they archetypes for builds? Is it problematic if they are archetypes for builds? Are they just flavor for settings and character backgrounds and other storytelling needs? Should they be? Why have "races" at all and not just "backgrounds"?

It's an interesting ongoing debate.