What symbolic message is the raven meant to send in the stories of Noah and Eliyahu?
As the floodwaters begin to subside, Noach sends the raven to check if living on the land has become once again viable (Bereishit 8:7). The Midrash relates a curious dialogue between Noach and the raven. The latter expressed its objection to having been selected for this mission over all the other creatures in the ark. Noach explained his reasoning to the raven: "What does the world need you for? You are neither edible nor fit to be offered as a sacrifice." God then reprimanded Noach for his insulting comments to the raven. He noted that one day a drought will ravage the Land of Israel, and the raven will bring food for Eliyahu Hanavi to help him survive the famine. (See Melakhim I 17:6).
What is this Midrash talking about?
One explanation offered takes a closer look at why God sent specifically the ravens to sustain Eliyahu during the drought. The Gemara in Masekhet Pesachim (113b) lists the raven as one of only three creatures that gets along with those of its same species. Whereas human beings and other creatures compete with those of their own kind, the ravens exhibit love and concern for one another. They therefore came to teach Eliyahu Hanavi a critical lesson. Eliyahu had decreed the drought during the time of the wicked king Achav, since he thought the generation to be worthless. After all, the people of his time had adopted idolatry. The ravens reminded Eliyahu of Noach's error in denying them any worth. In truth, they possess a quality whose importance may never be undermined: unity. Similarly, the generation of Achav worked together in love and harmony (Yerushalmi Pei'a 1:1). Although this quality does not excuse their pagan worship, it does afford the people of Achav's time a significant stature. This is the message of the ravens' bringing food to Eliyahu: Jewish unity sustained the generation of Achav by rendering them, at least in one sense, meritorious.
This serves an as a most appropriate message for Noach, as well. Chazal comment that God issued the destruction decree against Noach's generation specifically on account of the sin of theft. God therefore tells Noach, who bears the responsibility of starting the world anew, that friendship and harmony among people takes top priority. Even if the raven is inedible and unsuitable as a sacrifice, its kindness towards its peers renders it inherently valuable. So long as people work together kindly, mankind can continue to exist peacefully.