Is the first marriage contract considered valid, or does it need to be renewed, given that I did not complete the Sa'i of Hajj (Hajj Ifrad) at that time and performed it later?

The ruling on this matter differs between two scenarios:

First: If you performed the Sa'y after the Tawaf al-Qudum (Tawaf of Arrival), then you are not required to perform the Sa'y after the Tawaf al-Ifadah (Tawaf of Departure from Mina), and the marriage contract is valid.

Second: If you did not perform the Sa'y, then you are still in a state of ihram, and the marriage contract was concluded while in ihram. This marriage is invalid according to the majority of scholars and must be renewed. It is considered a dubious marriage (nikah shubhah) to which a child would be legitimately attributed.

The questioner is advised to gain a deeper understanding of the rulings of Hajj and Umrah and to consult with people of knowledge.