Despite the label "wildcard redirect," the basic DNS configuration at Namecheap does not redirect www or TLD requests. (Why? Beats me, it seems very wrong.) To accomplish any reasonable redirect you need to manually add entries for the TLD and www sub. Then you can add a wildcard to catch other subs. A correctly configured redirect is shown below.
To be fair, Namecheap does document this, but it's not entirely clear from their support page and sure isn't expected behavior based on the UI.