Sacrificed Lamb By Ibrahim عليه السلام
Yes but why was it then ordered to sacrifice a lamb afterwards?
You can say that because of imamat given to Prophet Abraham (AS) and His religious tradition was meant to be kept alive at a global level till the end of times.
Please read the references of Quran I shared above once again. Prophets acted on those dreams and later on it became clear that why those dreams were shown to the Prophets. Prophet Muhammad (sws) went for Umrah on the basis of dream shown in 48:27 and later Hudaibiya Agreement happened. Similary. Dream shown 8:43 was with the purpose so Muslims should feel motivated. Similary, dream shown in 37:102 was later manifested in the form of annual animal sacrifice ritual of Hajj.
I will be repeating myself if I respond to this, I am sure your point must have some merits to it.