Miracle, only in the sense of “Hashgacha Pratis.” Consider:
1. The Brits wanted to keep their Empire, but the Americans wouldn’t let them. By 1948 Britain was little better than a client state of the Americans. Remember the British plan was for the Israelis to lose and then ask Britain to return and save them, thereby showing how necessary the Empire was (same strategy used in Ireland and India, and failed everywhere).
2. The British and French had prevented the Arabs from building up Arab armies (since they didn’t trust them), so while Israel was invaded by “five” Arab armies, they were armies in name only – untrainined and poorly equipped. They had no meaningful naval or air forces. While the Israeli equipment was a “mash up”, Israel had a large number of well trained, combat experienced veterans including those who served in British units (both the ones recruited in Palestine and elsewhere), not to mention veterans of various resistance groups, and veterans of the various allied armies.
3. The Israelis were fighting on internal line, whereas the Arabs were split so, for example, the Egyptians couldn’t help the Syrians. The fact that the different Arab units couldn’t stand each other was also an asset.
4. Public opinion in the west strongly supported Israel. When the US arrested people for sending weapons to Israel, the juries refused to convict. While the Americans stayed neutral, and the Brits were still hoping to return, the rest of the world was anxious to see the Israelis win since it would bring down the British Empire once an for all, thus groups as divere as the Irish Republican Army, the Mafia, and the KGB helped the Israelis fet weapons.