Using jq how can I replace the name of a key with something else

Use the following jq approach:

jq '[.[] | .["fruit2"] = .veg | .["job"] = .worker | del(.veg, .worker)]' file

The output:

[
  {
    "fruit": "strawberry",
    "fruit2": "apple",
    "job": "gardener"
  }
]