the.com/digger

means A person or machine that excavates earth — digging holes, trenches, or tunnels, whether by shovel or hydraulic arm.

from Straightforward Old English stock: 'dig' (origin itself a bit murky, possibly linked to 'dike' and 'ditch') plus the agent suffix '-er', meaning 'one who does the verb.' The slang sense — an Australian/NZ term for a bloke, or WWI-era soldiers nicknamed 'diggers' for their trench work — rode in on the same literal image of someone with a shovel, long before it became an image of someone with a slightly-too-large hole.