Or the error is to assume that "the least of these, My brethren", only refers to Jews.
The poor, the oppressed, the widow, the orphan have always been the Lord's special people.
Isaiah 3:
13 The Lord stands up to plead,
And stands to judge the people.
14 The Lord will enter into judgment
With the elders of His people
And His princes: For you have eaten up the vineyard;
The plunder of the poor is in your houses.
15 What do you mean by crushing My people
And grinding the faces of the poor?
Says the Lord God of hosts.
Isaiah 61:1 The Spirit of the Lord God is upon Me,
Because the Lord has anointed Me
To preach good tidings to the poor;
He has sent Me to heal the brokenhearted,
To proclaim liberty to the captives,
And the opening of the prison to those who are bound;