A person who can turn their hand to loads of different jobs and usually does them alright, but isn’t truly brilliant at any single one. It can be a genuine compliment for being handy, or a cheeky dig if someone’s spreading themselves thin. Often said with the follow-up: master of none.
"Gaz fixed the leaky loo, bodged the dodgy socket, then built a wonky shed out of pallets. Proper Jack of all trades. Master of none, mind, but it’ll do"