In the released, blorbed-up Glulx file, figures and sound effects are internally given resource ID numbers which count upwards from 2 in order of their declaration. (Figure and sound numbers can thus be intermingled, if their declarations are.) Resource ID number 1 is reserved for the image of the cover art, if there is any.
In my projects, the resource ID numbers start from 3.
Is this a sign that something is wrong?
I have sounds (declared like Sound of Z is the file "Z.ogg".) but no images or other files.
Typically you shouldn’t have to care about the specific resource IDs that get assigned to any one thing. Within your source text you should only use the name to refer to a resource (since they can get renumbered if you move source around).
You do have to partly care about them when working with Parchment, but mostly only to the extent of getting a tool to automatically generate the resource map for you.