It seems Adam was not part of this assembly or the oath was not taken from him, because the phrase Children of Adam does not include him. Moreover, the expression: “or lest you say, “Verily, it was but our forefathers who, in times gone by, began to ascribe divinity to other beings beside God; and we were but their late offspring: wilt Thou, then, destroy us for the doings of those inventors of falsehoods?” cannot be said for Adam, he had no parents or forefathers.
Thirdly, this happening was removed from the memories of human being to put them to test of believing in One Unseen God following their nature which recognizes God as they did in that Assembly, but Adam did not forget seeing God during his stay in the heaven. so this test was for him, so could not be a part of it.