Translation:Come on, let's go.
It doesn' mean "now", it means like, well as in "ok moving on now", it seems like more of a conversation part rather than a sentence you'll find written down.
It's true that it is the same meaning in english, but the point is so you'll distinct between "now" as in time, than "well then"
さあ doesn't necessarily mean "Come on". It can be translated differently based on the context. Here we don't have much context.
さあ Conjunction 1. come; come now; come along; go on; hurry up 2. well; who knows; I don't know...; uh; hmm 3. well now; let's see; there we go; all rightsaid when surprised or happy 4. about that; you see
I used "Come, Let's go" and it was flagged as incorrect... Why would you need to add "on" after "Come"?
じゃ is a contraction of では, oftentimes used as an expression that you are reaching a conclusion, very similar to how you would use "well then" in english.. and さあ is an expression used in order to make the conversation move forward, this is often more forceful than じゃ, which also depends on the tone of context. You could translate さー as "ok now", "come on", "ok let's not dwell on it and move forward".
I don't know what you mean by "corrected", did it just say "another correct answer is..." and say this one? If so, then of course it said that, there can only be one default answer, and every time you stray away from that, even if you're correct, it tells you what it did want.
If it said you were wrong, then I think that it's right, as さあ is not a confirmation word, it's a conjunction that means exactly what duolingo is saying, "come on, "well", "there we go", and even "I don't know". If I'm wrong then someone could correct me on that though.
While we should understand how to USE さあ， knowing the exact (according to DL) translation is kind of dumb. It's so context sensitive. It's more about feeling than actual words, and it's not really possible to speak English the exact way you speak Japanese. This is a shortcoming of DL. Is it possible to restrict "saa" to Japanese entry instead of English entry? It's much easier to go that direction.
I think you don't have to use the word "we" or "us" because this is an informal sentence. You would say this to someone you're close to like your friend, sibling, or partner. Ikimasu would be used for a more singular and formal way of saying "I am going." Correct me if I'm wrong. ( • ͜ • ) "Mashou" is used in a suggestive way and used for an idea to your close listener, as I listed above. Don't know if this made sense or not but I hope this helps in a way!☆