The first time that Moshe Rabbeinu announced HaShem's promise to take the Jews out of Mitzrayim, everyone believed him and bowed to HaShem gratefully. But when they saw that this promise was not being fulfilled immediately, they became very disappointed. Their hard work made it difficult for them to listen to Moshe.
Moshe brought the message of geulah to Pharaoh alone. After the ten plagues, Pharaoh gave in and let the Jews go.
But even after they left Egypt, the Jews were still afraid of the Egyptians. Many Jews became so terrified when they were chased by the Egyptian army that they spoke of returning to the slavery in Egypt. They did not feel secure and free until after the Red Sea split.
Still, there was one group which stood out all along. These were the Jewish children who had learned to trust in HaShem from the time that He protected them from being killed by Egyptians.
The Jewish adults stood fearfully at the brink of the Red Sea, but the Jewish children were calm. They knew that HaShem would save them. Later, even young babies joyfully sang Az Yashir, praising HaShem for the great miracles of geulas Mitzrayim.
In many ways, Mashiach's coming will be like geulas Mitzrayim, and Jewish children will have a large share in it. We read, "Do not touch My anointed ones (meshichoi)." Our Sages tell us that the word meshichoi means the Jewish children. Why are children called with this name? Because they have the strongest desire for Mashiach to come.
Everyone wants Mashiach to come. But adults are busy with work and with paying bills. Children are not bothered with these worries and responsibilities. They can concentrate on what they really want, which is Mashiach. That is why children were the first to sing "We Want Mashiach Now."
The dictionary says that "want" also means a lack or a need. Jewish children feel that something is missing because Mashiach has not yet come.
But we will not have to wait much longer, because Mashiach is coming very soon. When he does come, as at the Red Sea, the children will recognize him first.
(Adapted from Sichos Simchas Torah, 5752)