A good explanation, but incomplete. I am a native English speaker doing the reverse tree, and the word WORK in English is used both as a verb and a noun:
WORK = trabajar o trabajo JOB = trabajo
Sin contexto, la frase 'I come to work' puede significar 'Vengo al lugar donde trabajo' o 'Vengo con el propósito de trabajar', o 'Empiezo a trabajar'. El primero es el significado más probable.
Without context, the sentence 'I come to work' can mean 'I come to the place where I work' or 'I come with the purpose of working' or 'I start to work'. The first is the most likely meaning. (I hope I translated that correctly)
You said 'I come from work = Vengo del trabajo. I think 'I come to work can also be 'Vengo al trabajo'. Of course, I'm not a native Spanish speaker, so please correct me if I'm wrong.
Duolingo has this messed up. They are misleading you to believe what you're suggesting is possible. It isn't. Trabajar is a verb. It can't be a place/lugar. The sustantivo is "el trabajo".
Notice how every one of the 18 definitions for trabajar starts with intr. (intransitive verb) or tr. (transitive verb)
But for trabajo all 12 main definitions begin with m. (masculino) because sustantivos /nouns have gender.
The portuguese version of this is better than what is here in spanish.
Correcto! Yo pensaba que VINE estaba correcto, pero no es así. Vine a trabajar es pasado vs vengo a trabajar es presente