"slave" means someone who cannot choose to stop working for another. If you can seek alternate employment or even just choose to stop working there, you're not a slave.
It's common practice to use the noun in a poetic sense, such as "wage slave" or "corporate slave", but such usage doesn't rise to expanding the definition of the word.
https://www.dictionary.com/browse/execute
"Execute" primarily means "carry out", not "kill". The latter definition is an adaption from the person designated to carry out the act of killing people for violating the law, which presumably at one point was done directly by the hereditary executive.