"We are helping the man."
Translation:Wir helfen dem Mann.
Can you have a German sentence without anything accusative
The simplest sentence just has a subject (in the nominative case) and a verb -- for example, Ich singe. "I am singing." No accusative needed.
And some verbs (such as helfen, danken, folgen) take an object in the dative case -- so you can have a sentence that has an object but still no accusative.
There's no requirement for accusative case to "complete" a sentence.