Is a son attributed to a father from a corrupt marriage considered his son in the sight of Allah and among his offspring in Paradise, or is this lineage a worldly ruling that does not express the true lineage in the sight of Allah?

Scholars have stipulated that every marriage which the spouses believe to be valid establishes lineage. Even if the marriage was invalid, the child's lineage is attributed to him, and they inherit from each other by the consensus of Muslims. This is a worldly ruling based on outward appearances. As for what concerns the Hereafter, its knowledge is with Allah Almighty.