That doesn't mean they weren't eventually treated as if they were fellow heirs with Jesus, along with Jews.
Oh heavens no. They were certainly heirs according to the promises. We are merely fellow heirs with them. They were saved exactly as we are. They just remained in their little groups, as Jews are used to doing. Look how hard it was for Peter and the others to be around gentiles. Antisemitism has always been with us.
1 Peter 2:12 Having your conversation honest among the Gentiles: that, whereas they speak against you as evildoers, they may by your good works, which they shall behold, glorify God in the day of visitation.