I don't know why this was downvoted, it seems like a reasonable question. I think the basic reason is that there is no word for "all" in the Hebrew. The words אתן and אתם mean "you (plural)", but not "all of you". I know some variants of American English would use "you all / y'all" in this context, but "Y'all are men" is not the same meaning as "You are all men."
Do nouns have the same plural endings for masculine and feminine, but verbs have different plural masculine and feminine endings? For instance, the nouns "men" and "women" have the same plural ending, but for the verb "see," the masculine and feminine plural endings are different. Is this always the case? Thank you!